Supplemental Prospectus (Form 424B5)

As Filed Pursuant to 424(b)(5)

Registration No. 333-290712

PROSPECTUS SUPPLEMENT

(To Prospectus Dated November 26, 2025)

$100,000,000

NOVABAY PHARMACEUTICALS, INC.

Common Stock

This prospectus supplement relates to the issuance and sale of shares of our common stock having an aggregate offering price of up to $100,000,000 from time to time through or to our sales agent, Virtu Americas LLC ("Virtu"). We have entered into an ATM Sales Agreement, or the sales agreement, with Virtu relating to the shares of our common stock offered by this prospectus supplement and the accompanying prospectus.

You should read this prospectus supplement, including any information incorporated herein by reference, carefully before you invest in our common stock.

Our common stock is listed on the NYSE American, LLC ("NYSE American"), under the symbol "NBY." On January 16, 2026, the closing price of our common stock as reported on NYSE American was $14.77 per share.

Sales of shares of our common stock, if any, under this prospectus supplement may be made by any method deemed to be an "at the market offering" as defined in Rule 415(a)(4) under the Securities Act of 1933, as amended (the "Securities Act"). Virtu is not required to sell any specific amount of securities, but will act as our sales agent using commercially reasonable efforts consistent with its normal trading and sales practices, on mutually agreed terms between Virtu and us. There is no arrangement for funds to be received in any escrow, trust or similar arrangement.

Unless we and Virtu otherwise agree, we will pay Virtu a commission of up to 2.0% of the gross proceeds of the shares of our common stock sold under the sales agreement. The net proceeds to us that we receive from sales of our common stock will depend on the number of shares actually sold and the offering price for such shares. We estimate the maximum total expenses, excluding commissions of Virtu, of this offering will be approximately $225,000.

In connection with the sale of common stock on our behalf, Virtu will be deemed to be an "underwriter" within the meaning of the Securities Act and the compensation of Virtu will be deemed to be underwriting commissions or discounts. We have agreed to provide indemnification and contribution to Virtu against certain liabilities, including liabilities under the Securities Act.

Investing in our common stock involves a high degree of risk. See "Risk Factors" beginning on page S-6.

Neither the Securities and Exchange Commission (the "SEC" or "Commission") nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus supplement. Any representation to the contrary is a criminal offense.

January 20, 2026

TABLE OF CONTENTS

PROSPECTUS SUPPLEMENT

			Page
PROSPECTUS SUPPLEMENT SUMMARY			S-2
NOVABAY PHARMACEUTICALS, INC.			S-2
THE OFFERING			S-5
RISK FACTORS			S-6
FORWARD-LOOKING STATEMENTS			S-8
USE OF PROCEEDS			S-10
DILUTION			S-11
PLAN OF DISTRIBUTION			S-12
DIVIDEND POLICY			S-13
LEGAL MATTERS			S-13
EXPERTS			S-13
WHERE YOU CAN FIND MORE INFORMATION			S-13
INCORPORATION OF CERTAIN INFORMATION BY REFERENCE			S-14

PROSPECTUS

ABOUT THIS PROSPECTUS	1
PROSPECTUS SUMMARY	2
RISK FACTORS	4
SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS	5
USE OF PROCEEDS	6
DESCRIPTION OF CAPITAL STOCK	7
DESCRIPTION OF DEBT SECURITIES	15
DESCRIPTION OF WARRANTS	22
DESCRIPTION OF UNITS	24
LEGAL OWNERSHIP OF SECURITIES	25
PLAN OF DISTRIBUTION	29
LEGAL MATTERS	31
EXPERTS	31
WHERE YOU CAN FIND MORE INFORMATION	31
INCORPORATION OF CERTAIN INFORMATION BY REFERENCE	32

PROSPECTUS

ABOUT THIS PROSPECTUS SUPPLEMENT

This prospectus supplement and the accompanying prospectus relates to part of a "shelf" registration statement on Form S-3 that was initially filed with the SEC on October 3, 2025, as amended on November 25, 2025. By using a shelf registration statement, we may, from time to time, sell any combination of the securities described in the above-referenced registration statement. This prospectus supplement and the accompanying prospectus include or incorporate by reference important information about us, our common stock, and other matters you should know before investing. You should read both this prospectus supplement and the accompanying prospectus as well as additional information described under "Where You Can Find More Information" in this prospectus supplement before making an investment decision.

You should rely only on this prospectus supplement, the accompanying prospectus and the information incorporated or deemed to be incorporated by reference in this prospectus supplement, the accompanying prospectus or in any free writing prospectuses we provide you. We have not, and Virtu has not, authorized anyone to provide you with information that is in addition to, or different from, that contained or incorporated by reference in this prospectus supplement, the accompanying prospectus or in any free writing prospectuses we have provided you. If anyone provides you with different or inconsistent information, you should not rely on it. We are not, and Virtu is not, offering to sell securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information in this prospectus supplement, the accompanying prospectus or any related free writing prospectus is accurate only as of the date on the front of those respective documents, or in the case of the documents incorporated by reference herein or therein, the date of such documents, in each case, regardless of the time of delivery of this prospectus supplement, the accompanying prospectus or any related free writing prospectus, or any sale of shares of our common stock. Our business, financial condition, liquidity, results of operations, and prospects may have changed since those dates.

The terms "NovaBay," the "Company," "we," "us," "our" and similar names refer to NovaBay Pharmaceuticals, Inc. and its consolidated subsidiary, unless we state otherwise or the context otherwise requires.

RISK FACTORS

Investing in our common stock involves a high degree of risk. For a discussion of the cautionary information you should carefully consider before deciding to purchase any shares of our common stock, please review the risk factors included in the documents incorporated by reference in this prospectus supplement, including "Part I, Item 1A-Risk Factors" in our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, filed with the SEC on April 2, 2025, as well as any amendment or update to our risk factors reflected in subsequent filings with the SEC, including in our Quarterly Reports on Form 10-Q or Current Reports on Form 8-K. The risks and uncertainties described in the documents incorporated by reference are not the only risks and uncertainties we face. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also impair our business operations. If negative events occur, our business, financial condition, results of operations and prospects would suffer. In that event, the market price of our common stock could decline, and you may lose all or part of your investment in our common stock.

Risks Related to This Offering

You may experience immediate and substantial dilution in the book value per share of the common stock you purchase in the offering.

The shares sold in this offering, if any, will be sold from time to time at various prices. The offering price per share in this offering may exceed the net tangible book value per share of our common stock outstanding prior to this offering. The future exercise of warrants for shares of our common stock and the exercise of outstanding stock options following the date of this prospectus supplement may result in dilution of your investment depending upon the actual price per share when shares are sold under this offering.

If you purchase shares of our common stock in this offering, you may experience future dilution as a result of future equity offerings.

In order to raise additional capital, we may in the future offer additional shares of our common stock or other securities convertible into or exchangeable for shares of our common stock. We cannot assure you that we will be able to sell shares or other securities in any other offering at a price per share that is equal to or greater than the price per share paid by investors in this offering, and investors purchasing shares of our common stock or other securities in the future could have rights superior to existing stockholders. The price per share at which we sell additional shares of our common stock or other securities convertible into or exchangeable for shares of our common stock in future transactions may be higher or lower than the price per share of our common stock in this offering.

We have broad discretion in the use of the net proceeds from this offering and may not use them effectively.

We cannot specify with certainty the particular uses of the net proceeds we will receive from this offering. Our management will have broad discretion in the application of the net proceeds, including for any of the purposes described in "Use of Proceeds" beginning on page S-10. Accordingly, you will have to rely upon the judgment of our management with respect to the use of the proceeds, with only limited information concerning management's specific intentions. Our management may spend a portion or all of the net proceeds from this offering in ways that our stockholders may not desire or that may not yield a favorable return. The failure by our management to apply these funds effectively could harm our business, financial condition, results of operations and prospects. Pending their use, we may invest the net proceeds from this offering in a manner that does not produce income or that loses value.

We will primarily use the net proceeds from this offering to purchase additional SKY, the price of which has been, and will likely continue to be, highly volatile.

We will primarily use the net proceeds from this offering to purchase additional SKY. SKY is a highly volatile asset that has traded below $0.0344 per SKY and above $0.09964 per SKY in the 12 months preceding the date of this prospectus supplement. In addition, SKY does not pay interest or other returns and so the ability to generate a return on investment from the net proceeds from this offering will depend on whether there is appreciation in the value of SKY following our purchases of SKY with the net proceeds from this offering. Future fluctuations in SKY trading prices may result in our converting SKY purchased with the net proceeds from this offering into cash with a value substantially below the net proceeds from this offering.

It is not possible to predict the actual number of shares of common stock we will sell under the sales agreement, or the gross proceeds resulting from those sales.

Subject to certain limitations in the sales agreement and compliance with applicable law, we have the discretion to deliver a placement notice to Virtu at any time throughout the term of the sales agreement. The number of shares of common stock that are sold through or to Virtu after delivering a placement notice will fluctuate based on a number of factors, including the market price of the common stock during the sales period, the limits we set with Virtu in any applicable placement notice, and the demand for our common stock during the sales period. Because the price per share of each share of common stock sold will fluctuate during the sales period, it is not currently possible to predict the number of shares that we will sell or the gross proceeds we will receive in connection with those sales.

The common stock offered hereby will be sold in "at the market offerings", and investors who buy shares at different times will likely pay different prices.

Investors who purchase shares of common stock in this offering at different times will likely pay different prices and so may experience different levels of dilution and different outcomes in their investment results. We will have discretion, subject to market demand, to vary the timing, prices, and numbers of shares of common stock sold in this offering. In addition, there is no minimum or maximum sales price for shares of common stock to be sold in this offering. Investors may experience a decline in the value of the shares they purchase in this offering as a result of sales made at prices lower than the prices they paid.

Offers of new securities or availability for sale of a substantial number of shares of our common stock, including as a result of the exercise of outstanding warrants may cause the price of our publicly traded securities to decline.

Sales of a significant number of shares of our common stock in the public market could depress the market price of our common stock. The pre-funded warrants issued January 16, 2026, will be convertible, in the aggregate, into approximately 87% of the total number of shares of common stock outstanding on a fully diluted basis. In addition, we could sell up to 6,770,480 shares of common stock pursuant to the ATM Sales Agreement, assuming a sale price of $14.77, the last reported price of our common stock on the NYSE American before the date of this prospectus supplement. If the market price of our common stock declines, this number could increase. Such sales could be significant and have a significant adverse impact on the price of our common stock.

Our highly volatile stock price may adversely affect the liquidity of the common stock you purchase in the offering.

The market price of our common stock has generally been highly volatile and is likely to continue to be highly volatile. For instance, the market price of our common stock has ranged from $0.58 to $19.16 per share over the last six months. Additionally, given the variability in trading price, our market capitalization may not correlate with the underlying book value of the assets we hold.

The market price of our common stock may be significantly impacted by many factors including the following:

	●	fluctuations in the price of SKY, of which we have significant holdings and with respect to which we expect to continue to make significant future purchases, and potential fair value changes associated therewith;
	●	any sales by us of our SKY at prices above or below their carrying value, which would result in our recording gains or losses upon sale of our SKY;
	●	the pace of adoption of blockchain-based financial infrastructure and related ecosystem services;
	●	a decrease in the price of other digital assets, including stablecoins, or the crash or unavailability of stablecoins that are used as a medium of exchange for SKY purchase and sale transactions, to the extent the decrease in the price of such other digital assets or the unavailability of such stablecoins may cause a decrease in the price of SKY or adversely affect investor confidence in digital assets generally;

	●	the success of our multi-year capital allocation strategy focused on acquiring and holding a portfolio of select digital assets;
	●	our ability to meet our revenue guidance;
	●	the offering and sale of shares of our common stock, either sold at market prices or at a discount under an equity transaction;
	●	significant changes in our capital structure;
	●	published reports by securities analysts;
	●	the occurrence of any significant litigation, disputes and other legal or regulatory proceedings;
	●	regulatory, commercial, and technical developments related to SKY, or digital assets more generally;
	●	general stock trends in the digital asset sector; and
	●	economic trends and other external factors including, but not limited to, interest rate fluctuations, economic recession, inflation, foreign market trends, national crisis, and disasters.

FORWARD-LOOKING STATEMENTS

This prospectus supplement, the accompanying prospectus and the other documents we have filed with the SEC that are incorporated herein by reference, contain forward-looking statements. Forward-looking statements are neither historical facts nor assurances of future performance. Instead, they are based on our current beliefs, expectations and assumptions regarding the future of our business, future plans and strategies and other future conditions. The words "aim," "anticipate," "believe," "contemplate," "continue," "could," "estimate," "expect," "goal," "intend," "may," "on track," "seek," "plan," "possible," "potential," "predict," "project," "seek," "should," "target," "will," "would," or the negative of these terms or other similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words.

These forward-looking statements include, among other things, statements about:

	●	volatility, liquidity, pricing, and market acceptance of SKY and other digital assets;
	●	changes to protocol design, governance, parameters, or economics (including issuance, fee structures, staking or buyback mechanisms);
	●	the pace of adoption of blockchain-based financial infrastructure and related ecosystem services;
	●	counterparty performance and the availability, reliability, security, and resiliency of third-party service providers, including custodians, trading venues, market makers, execution and settlement partners, data providers, and technology vendors;
	●	cybersecurity incidents, operational failures, loss or compromise of private keys, and other safeguarding risks;
	●	our ability to identify, diligence, consummate, integrate, and manage acquisitions consistent with our risk framework and liquidity needs;
	●	macroeconomic and market conditions;
	●	the impact of domestic and international laws, regulations, regulatory guidance, rulemaking, enforcement actions, and licensing or registration requirements applicable to digital assets, market structure, custody, broker-dealer and commodities or derivatives activities, sanctions, AML/KYC, tax, and consumer protection;
	●	accounting standards developments and interpretations (including the effects of our adoption of ASU 2023-08);
	●	tax consequences and reporting requirements;
	●	our liquidity, capital resources, access to financing, and the terms and availability of any financing or hedging arrangements; and
	●	Board and Investment Committee decisions and governance processes.

We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements we make. In particular, you should consider the numerous risks described in our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, as filed with the SEC on April 2, 2025, which is incorporated by reference in this prospectus supplement, and any other documents we file with the SEC, including such risks included in Exhibit 99.1 to the Current Report on Form 8-K, filed with the SEC on January 16, 2026, that are deemed incorporated by reference into this prospectus supplement and the accompanying prospectus and are included in the "Risk Factors" beginning on page S-6. See "Where You Can Find More Information." Our forward-looking statements do not reflect the potential impact of any future acquisitions, mergers, dispositions, joint ventures or investments we make.

We cannot guarantee future results, level of activity, performance or achievements. You should not rely upon forward-looking statements as predictions of future events. Unless required by law, we will not undertake and we specifically disclaim any obligation to release publicly the result of any revisions which may be made to any forward-looking statements to reflect events or circumstances after the date of such statements or to reflect the occurrence of events, whether or not anticipated. In that respect, we wish to caution readers not to place undue reliance on any such forward-looking statements, which speak only as of the date they are made.

USE OF PROCEEDS

From time to time, we may sell shares of our common stock pursuant to the sales agreement with Virtu, which may result in aggregate gross proceeds of up to $100,000,000 and aggregate net proceeds of approximately $97,775,000. Because there is no minimum amount of shares of our common stock that must be sold pursuant to our sales agreement with Virtu, the actual number of shares of our common stock sold and aggregate net proceeds to us are not presently determinable and may be substantially less than the amounts set forth above.

We intend to use the net proceeds from this offering for general corporate purposes, including but not limited to supporting a multi-year capital allocation strategy focused on acquiring and holding a portfolio of select digital assets that exhibit revenue-generating characteristics, consistent with our operating and risk framework, with SKY being the first approved asset to date.

DILUTION

If you invest in our common stock, your interest will be diluted to the extent of the difference between the price per share you pay in this offering and the net tangible book value per share of our common stock immediately after this offering.

Our net tangible book value as of September 30, 2025 was approximately $1.6 million, or approximately $0.27 per share of common stock. Our net tangible book value is the amount of our total tangible assets less our total liabilities. Net tangible book value per share represents net tangible book value divided by the 6,010,749 shares of common stock outstanding as of September 30, 2025.

Dilution per share to new investors represents the difference between the amount per share paid by purchasers for our common stock in this offering and the net tangible book value per share of our common stock immediately following the completion of this offering. After giving effect to the sale of our common stock offered by this prospectus supplement at an assumed offering price of $14.77 per share of common stock (the last reported sale price of our common stock on the NYSE American on January 16, 2026), and after deduction of commissions and estimated aggregate offering expenses payable by us, our as adjusted net tangible book value as of September 30, 2025 would have been $99 million, or $7.78 per share. This represents an immediate increase in net tangible book value of $7.51 per share to our existing stockholders and an immediate dilution in as adjusted net tangible book value of $6.99 per share to new investors in this offering.

The following table illustrates this dilution on a per share basis:

Offering price per share						$	14.77	(1)
Net tangible book value per share as of September 30, 2025		$	0.27
Increase in net tangible book value per share attributable to the offering		$	7.51
As-adjusted net tangible book value per share after giving effect to the offering						$	7.78
Dilution in net tangible book value per share to new investors in this offering						$	6.99

(1) Assuming a purchase price of $14.77, the closing price per share of our common stock on January 16, 2026.

The table and discussion above are based on 6,010,749 shares of our common stock outstanding on September 30, 2025, and exclude:

	●	1,022 shares of common stock reserved for issuance upon the exercise of stock options outstanding as of September 30, 2025 under our 2017 Omnibus Incentive Plan (the "2017 Plan") at a weighted average exercise price of $448.84 per share; and
	●	101,191 shares of common stock reserved for issuance upon the exercise of warrants to purchase shares of common stock outstanding as of September 30, 2025, at a weighted average exercise price of $66.61 per share.

To the extent that outstanding stock options or warrants are exercised, new stock options or warrants are issued, or we issue additional shares of common stock in the future, there will be further dilution to investors. In addition, we may choose to raise additional capital because of market conditions or strategic considerations, even if we believe that we have sufficient funds for our current or future operating plans. If we raise additional capital through the sale of equity or convertible debt securities, the issuance of these securities could result in further dilution to our stockholders.

PLAN OF DISTRIBUTION

We have entered into the ATM Sales Agreement with Virtu, under which we may offer and sell our shares of common stock from time to time through or to Virtu acting as agent or principal. Pursuant to this prospectus supplement, we may offer and sell up to $100,000,000 of our shares of common stock. Sales of our shares of common stock, if any, under this prospectus supplement and the accompanying prospectus will be made by any method that is deemed to be an "at the market offering" as defined in Rule 415(a)(4) under the Securities Act.

Each time we wish to issue and sell shares of common stock under the ATM Sales Agreement, we will notify Virtu of the number of shares to be issued, the dates on which such sales are anticipated to be made, any limitation on the number of shares to be sold in any one day and any minimum price below which sales may not be made. Once we have so instructed Virtu, unless Virtu declines to accept the terms of such notice, Virtu has agreed to use its commercially reasonable efforts consistent with its normal trading and sales practices to sell such shares up to the amount specified on such terms. The obligations of Virtu under the ATM Sales Agreement to sell our shares of common stock are subject to a number of conditions that we must meet.

The settlement of sales of shares between us and Virtu is generally anticipated to occur on the first trading day following the date on which the sale was made. Sales of our shares of common stock as contemplated in this prospectus supplement will be settled through the facilities of The Depository Trust Company or by such other means as we and Virtu may agree upon. There is no arrangement for funds to be received in an escrow, trust, or similar arrangement.

We will pay Virtu a commission of up to 2.0% of the aggregate gross proceeds we receive from each sale of our shares of common stock. Because there is no minimum offering amount required as a condition to close this offering, the actual total public offering amount, commissions and proceeds to us, if any, are not determinable at this time. In addition, we have agreed to reimburse Virtu for the fees and disbursements of its counsel, payable upon execution of the ATM Sales Agreement, in an amount not to exceed $50,000. In addition to such fees, at the end of each quarter in which the offering is open and during which sales of our common stock have occurred, we have agreed to pay Virtu's legal counsel an additional legal fee equal to $5,000. We estimate that the total expenses for the offering, excluding any commissions or expense reimbursement payable to Virtu under the terms of the ATM Sales Agreement, will be approximately $225,000. The remaining sale proceeds, after deducting any other transaction fees, will equal our net proceeds from the sale of such shares.

Virtu will provide confirmation to us before the open on the NYSE American on the day following each day on which shares of common stock are sold under the ATM Sales Agreement.

In connection with the sale of the shares of common stock on our behalf, Virtu will be deemed to be an "underwriter" within the meaning of the Securities Act, and the compensation of Virtu will be deemed to be underwriting commissions or discounts. We have agreed to indemnify Virtu against certain civil liabilities, including liabilities under the Securities Act. We have also agreed to contribute to payments Virtu may be required to make in respect of such liabilities.

This offering of our shares of common stock pursuant to the ATM Sales Agreement will terminate upon the earlier of (i) the sale of all shares of common stock subject to the ATM Sales Agreement; or (ii) the termination of the ATM Sales Agreement as permitted therein. We and Virtu may each terminate the ATM Sales Agreement at any time upon three days' prior notice.

This summary of the material provisions of the ATM Sales Agreement does not purport to be a complete statement of its terms and conditions. A copy of the ATM Sales Agreement will be filed as an exhibit to a current report on Form 8-K filed under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and will be incorporated by reference in this prospectus supplement.

Virtu and its affiliates may in the future provide various investment banking, commercial banking, financial advisory and other financial services for us and our affiliates, for which services they may in the future receive customary fees. In the course of its business, Virtu may actively trade our securities for its own account or for the accounts of customers, and, accordingly, Virtu may at any time hold long or short positions in such securities.

A prospectus supplement and the accompanying prospectus in electronic format may be made available on a website maintained by Virtu, and Virtu may distribute the prospectus supplement and the accompanying prospectus electronically.

DIVIDEND POLICY

On August 26, 2025, the Special Transaction Committee of the Board of Directors and our Board of Directors declared a special cash dividend of $0.80 per share for our common stock. The dividend totaling $4.8 million was paid on September 29, 2025 to stockholders of record of common stock and certain preferred stock at the close of business on September 15, 2025. We otherwise intend to retain future earnings, if any, to finance the operating and expansion of our business and do not anticipate paying any cash dividends in the foreseeable future. Any future determination related to our dividend policy will be made at the discretion of our board of directors after considering our financial condition, results of operations, capital requirements, business prospects and other factors our board of directors deems relevant, and subject to the restrictions contained in our current and any future financing instruments. Our ability to pay cash dividends on our capital stock in the future may also be limited by the terms of any preferred securities we may issue or agreements governing any indebtedness we may incur.

LEGAL MATTERS

The validity of the shares of common stock offered by this prospectus supplement will be passed upon for us by Ropes & Gray LLP, New York, New York. Virtu is being represented in connection with this offering by Duane Morris LLP, New York, New York.

EXPERTS

The consolidated financial statements of NovaBay Pharmaceuticals, Inc. as of December 31, 2024 and 2023, and for the years then ended, incorporated by reference in this prospectus supplement, have been audited by WithumSmith+Brown, PC, an independent registered public accounting firm, as stated in their report. Such consolidated financial statements are incorporated by reference in reliance upon the report of such firm given their authority as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

We have filed a registration statement on Form S-3 with the SEC registering the offer and sale of our common stock offered by this prospectus supplement and the accompanying prospectus. This prospectus supplement and the accompanying prospectus do not include all of the information contained in the registration statement. You should refer to the registration statement, its exhibits and the information incorporated in this prospectus supplement and the accompanying prospectus for additional information.

We file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public from the SEC's website at http://www.sec.gov.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

The SEC's rules allow us to "incorporate by reference" information we have filed with the SEC, which means that we can disclose important information by referring you to those documents. The information incorporated by reference is a part of this prospectus supplement and the accompanying prospectus, and information that we file later with the SEC will automatically update and supersede the information included and/or incorporated by reference in this prospectus supplement and the accompanying prospectus. We incorporate by reference into this prospectus supplement the documents listed below and any future filings made by us with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended (other than, in each case, any document or portion of a document that is deemed not to be filed) after the initial filing of the accompanying prospectus that contains this prospectus and prior to the time that we sell all of the securities offered by this prospectus supplement or otherwise terminate this offering:

●	Our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, filed with the SEC on April 2, 2025;
●	our Quarterly Reports on Form 10-Q for the fiscal periods ended March 31, 2025, June 30, 2025 and September 30, 2025, filed with the SEC on May 15, 2025, August 14, 2025 and November 7, 2025, respectively;
●	our Current Reports on Form 8-K, filed with the SEC on January 10, 2025, January 22, 2025, January 23, 2025, February 4, 2025, March 7, 2025, March 11, 2025, April 22, 2025, August 19, 2025, August 26, 2025, October 9, 2025, October 20, 2025, October 21, 2025, October 22, 2025 and January 16, 2026 (in each case, except for information contained therein which is furnished rather than filed); and
●	the description of our common stock contained in our Registration Statement on Form 8-A, as filed with the SEC on August 29, 2007, as updated and superseded by the description of our common stock contained in Exhibit 4.1 to our Annual Report on Form 10-K for the fiscal year ended December 31, 2024 and any amendment or report filed for the purpose of updating such description.

You may obtain documents incorporated by reference into this prospectus supplement at no cost by requesting them in writing or telephoning us at the following address:

Attn: Tommy Law

NovaBay Pharmaceuticals, Inc.

2000 Powell Street, Suite 1150

Emeryville, CA 94608

(510) 899-8800 ext. 138

Prospectus

$200,000,000

Common Stock

Preferred Stock

Debt Securities

Warrants

Units

From time to time, we may offer and sell up to $200,000,000 of any combination of our common stock, preferred stock, debt securities, warrants or units described in this prospectus, either individually or in combination. We may also offer common stock or preferred stock upon the conversion of debt securities, common stock upon the conversion of preferred stock, or common stock, preferred stock or debt securities upon the exercise of warrants.

This prospectus describes the general terms of these securities and the general manner in which these securities will be offered. We will provide the specific terms of these offerings and securities in one or more supplements to this prospectus. We may also authorize one or more free writing prospectuses to be provided to you in connection with these offerings. The prospectus supplement and any related free writing prospectus may also add, update or change information contained in this prospectus. You should carefully read this prospectus, the applicable prospectus supplement and any related free writing prospectus, as well as any documents incorporated by reference, before buying any of the securities being offered.

The securities may be sold directly by us to investors, through agents designated from time to time or to or through underwriters or dealers, on a continuous or delayed basis. For additional information on the methods of sale, you should refer to the section entitled "Plan of Distribution" in this prospectus. If any agents or underwriters are involved in the sale of any securities with respect to which this prospectus is being delivered, the names of such agents or underwriters and any applicable fees, commissions, discounts and over-allotment options will be set forth in a prospectus supplement. The price to the public of such securities and the net proceeds we expect to receive from such sale will also be set forth in a prospectus supplement.

Our common stock is listed on the NYSE American under the trading symbol "NBY." The applicable prospectus supplement will contain information, where applicable, as to other listings, if any, on the NYSE American or other securities exchange of the securities covered by the applicable prospectus supplement. Prospective purchasers of our securities are urged to obtain current information as to the market prices of our securities, where applicable. As of November 24, 2025, the aggregate market value of our outstanding common stock held by non-affiliates is approximately $5.9 million, based on 126,010,749 shares of outstanding common stock, of which approximately 6,007,881 shares are held by non-affiliates, and a per share price of $0.99 based on the closing sale price of our common stock on November 20, 2025. Pursuant to General Instruction I.B.6 of Form S-3, in no event will we sell the securities described in this prospectus in a primary public offering with a value exceeding more than one-third of the aggregate market value of our common stock held by non-affiliates in the twelve-month period prior to the date of the sale of any such securities, so long as the aggregate market value of our outstanding common stock held by non-affiliates remains below $75.0 million.

Investing in our securities involves a high degree of risk. Before deciding whether to invest in our securities, you should consider carefully the risks that we have described under the caption "Risk Factors" on page 4. We may include specific risk factors in supplements to this prospectus under the caption "Risk Factors." This prospectus may not be used to sell our securities unless accompanied by a prospectus supplement.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus is November 26, 2025.

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement on Form S-3 that we filed with the Securities and Exchange Commission, or SEC, utilizing a "shelf" registration process. Under this shelf registration process, we may offer and sell, either individually or in combination, in one or more offerings, up to a total dollar amount of $200,000,000 of any combination of the securities described in this prospectus.

This prospectus provides you with a general description of the securities we may offer. Each time we offer securities under this prospectus, we will provide a prospectus supplement that will contain more specific information about the terms of that offering. We may also authorize one or more free writing prospectuses to be provided to you that may contain material information relating to these offerings. The prospectus supplement and any related free writing prospectus that we may authorize to be provided to you may also add, update or change any of the information contained in this prospectus or in the documents that we have incorporated by reference into this prospectus. We urge you to read carefully this prospectus, any applicable prospectus supplement and any free writing prospectuses we have authorized for use in connection with a specific offering, together with the information incorporated herein by reference as described under the heading "Incorporation of Certain Information by Reference," before buying any of the securities being offered.

This prospectus does not contain all of the information that is in the registration statement. We omitted certain parts of the registration statement from this prospectus as permitted by the SEC. We refer you to the registration statement and its exhibits for additional information about us and the securities that may be sold under this prospectus.

This prospectus may not be used to consummate a sale of securities unless it is accompanied by a prospectus supplement.

You should rely only on the information contained in, or incorporated by reference into, this prospectus and any applicable prospectus supplement, along with the information contained in any free writing prospectuses we have authorized for use in connection with a specific offering. We have not authorized anyone to provide you with different or additional information. If anyone provides you with different or inconsistent information, you should not rely on it. This prospectus is an offer to sell only the securities offered hereby, but only under circumstances and in jurisdictions where it is lawful to do so.

The information appearing in this prospectus, any applicable prospectus supplement or any related free writing prospectus is accurate only as of the date on the front of the document and that any information we have incorporated by reference is accurate only as of the date of the document incorporated by reference, regardless of the time of delivery of this prospectus, any applicable prospectus supplement or any related free writing prospectus, or any sale of a security. Our business, financial condition, results of operations and prospects may have changed since those dates.

This prospectus contains summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been filed, will be filed or will be incorporated by reference as exhibits to the registration statement of which this prospectus is a part, and you may obtain copies of those documents as described below under the section entitled "Where You Can Find More Information."

This prospectus and the information incorporated herein by reference include trademarks, service marks and trade names owned by us or other companies. All trademarks, service marks and trade names included or incorporated by reference into this prospectus, any applicable prospectus supplement or any related free writing prospectus are the property of their respective owners.

Unless the context indicates otherwise in this prospectus, the terms "NovaBay," the "Company," the "Registrant," "we," "our" or "us" in this prospectus refer to NovaBay Pharmaceuticals, Inc.

PROSPECTUS SUMMARY

This summary highlights selected information contained elsewhere in this prospectus or incorporated by reference in this prospectus, and does not contain all of the information that you need to consider in making your investment decision. You should carefully read the entire prospectus, the applicable prospectus supplement and any related free writing prospectus, including the risks of investing in our securities discussed under the heading "Risk Factors" contained in the applicable prospectus supplement and any related free writing prospectus, and under similar headings in the other documents that are incorporated by reference into this prospectus. Each of the risk factors could adversely affect our business, operating results and financial conditions, as well as adversely affect the value of an investment in our securities.

Overview

NovaBay Pharmaceuticals (the "Registrant") is currently transitioning from a former focus on eyecare and wound care products toward a structural repositioning following the sale of all operational product lines. On January 8, 2025, we completed the divestiture of our wound care trademarks (NeutroPhase® and PhaseOne®), and on January 17, 2025, we completed the sale of our eyecare business assets, including Avenova® brand.

For the fiscal year ended December 31, 2024, our revenue from continuing operations was approximately $9.7 million, primarily attributable to sales of eyecare products before disposition, and we recorded a decrease in wound care product revenue compared to 2023.

Following these strategic divestitures, NovaBay is repositioning its business model and evaluating new opportunities and potential strategic transactions. As part of its broader capital allocation review, the Company has begun evaluating opportunities within emerging financial infrastructure and network-based markets. These opportunities may include select blockchain-based assets that the Registrant believes could enhance capital efficiency and long-term stockholder value.

Additional Information

For additional information related to our business and operations, please refer to the reports incorporated herein by reference, including our most recent Annual Report on Form 10-K, as amended, and Quarterly Report on Form 10-Q, as described under the caption "Incorporation of Certain Information by Reference."

Registrant Information

Our corporate address is 2000 Powell Street, Suite 1150, Emeryville, California 94608, and our telephone number is (510) 899-8838. Our website address is www.novabay.com. Information found on, or accessible through, our website is not a part of, and is not incorporated into, this prospectus, and you should not consider it part of this prospectus. Our website address is included in this document as an inactive textual reference only.

The Securities We May Offer

We may offer shares of our common stock and preferred stock, various series of debt securities, warrants to purchase any of such securities and/or units, either individually or in combination, up to a total dollar amount of $200,000,000, from time to time under this prospectus, together with the applicable prospectus supplement and any related free writing prospectus, at prices and on terms to be determined by market conditions at the time of any offering. We may also offer common stock, preferred stock and/or debt securities upon the exercise of warrants. This prospectus provides you with a general description of the securities we may offer. Each time we offer a type or series of securities under this prospectus, we will provide a prospectus supplement that will describe the specific amounts, prices and other important terms of the securities, including, to the extent applicable:

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designation or classification;

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aggregate principal amount or aggregate offering price;

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maturity date, if applicable;

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original issue discount, if any;

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rates and times of payment of interest or dividends, if any;

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redemption, conversion, exercise, exchange or sinking fund terms, if any;

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conversion or exchange prices or rates, if any, and, if applicable, any provisions for changes to or adjustments in the conversion or exchange prices or rates and in the securities or other property receivable upon conversion or exchange;

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ranking;

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restrictive covenants, if any;

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voting or other rights, if any; and

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material or special U.S. federal income tax considerations, if any.

The applicable prospectus supplement and any related free writing prospectus that we may authorize to be provided to you may also add, update or change any of the information contained in this prospectus or in the documents we have incorporated by reference. However, no prospectus supplement or free writing prospectus will offer a security that is not registered and described in this prospectus at the time of the effectiveness of the registration statement of which this prospectus is a part.

We may sell the securities directly to investors or to or through agents, underwriters or dealers. We, and our agents or underwriters, reserve the right to accept or reject all or part of any proposed purchase of securities. If we do offer securities to or through agents or underwriters, we will include in the applicable prospectus supplement:

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the names of those agents or underwriters;

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applicable fees, discounts and commissions to be paid to them;

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details regarding over-allotment options, if any; and

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the net proceeds to us.

THIS PROSPECTUS MAY NOT BE USED TO CONSUMMATE A SALE OF SECURITIES UNLESS IT IS ACCOMPANIED BY A PROSPECTUS SUPPLEMENT.

RISK FACTORS

Investing in our securities involves a high degree of risk. Before deciding whether to invest in our securities, you should consider carefully the risks and uncertainties described under the heading "Risk Factors" contained in the applicable prospectus supplement and any related free writing prospectus, and discussed under the section entitled "Risk Factors" contained in our most recent Annual Report on Form 10-K, as amended, and in our most recent Quarterly Report on Form 10-Q and other filings made pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act, as well as any amendments thereto reflected in any such subsequent filings with the SEC, which are incorporated by reference into this prospectus in their entirety, together with other information in this prospectus, the documents incorporated by reference and any free writing prospectus that we may authorize for use in connection with this offering. See "Where You Can Find More Information."

The risks described in these documents are not the only ones we face, but those that we consider to be material based on the information currently known to us. There may be other unknown or unpredictable economic, business, competitive, regulatory or other factors that could have material adverse effects on our future results. Past financial performance may not be a reliable indicator of future performance, and historical trends should not be used to anticipate results or trends in future periods. If any of these risks actually occurs, our business, financial condition, results of operations or cash flow could be seriously harmed. This could cause the trading price of our common stock to decline, resulting in a loss of all or part of your investment. Please also read carefully the section below entitled "Special Note Regarding Forward-Looking Statements."

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus and the documents we have filed with the SEC that are incorporated by reference contain "forward-looking statements" within the meaning of Section 27A of the Securities Act and Section 21E of the Securities Exchange Act of 1934 (the "Exchange Act"). These statements relate to future events or to our future operating or financial performance and involve known and unknown risks, uncertainties and other factors which may cause our actual results, performance or achievements to be materially different from any future results, performances or achievements expressed or implied by the forward-looking statements.

In some cases, you can identify forward-looking statements by terms such as "may," "will," "should," "could," "would," "expects," "plans," "anticipates," "believes," "estimates," "projects," "predicts," "potential" and similar expressions intended to identify forward-looking statements. These statements reflect our current views with respect to future events and are based on assumptions and are subject to risks and uncertainties. Given these uncertainties, you should not place undue reliance on these forward-looking statements.

We discuss in greater detail many of these risks under the heading "Risk Factors" contained in the applicable prospectus supplement, in any free writing prospectuses we may authorize for use in connection with a specific offering, and in our most recent Annual Report on Form 10-K, as amended, and in our most recent Quarterly Report on Form 10-Q, as well as any amendments thereto reflected in subsequent filings with the SEC, which are incorporated by reference into this prospectus in their entirety. Also, these forward-looking statements represent our estimates and assumptions only as of the date of the document containing the applicable statement. Unless required by law, we undertake no obligation to update or revise any forward-looking statements to reflect new information or future events or developments, unless required by law to do so. Thus, you should not assume that our silence over time means that actual events are bearing out as expressed or implied in such forward-looking statements. You should read this prospectus, any applicable prospectus supplement, together with the documents we have filed with the SEC that are incorporated by reference and any free writing prospectus that we may authorize for use in connection with this offering completely and with the understanding that our actual future results may be materially different from what we expect. We qualify all of the forward-looking statements in the foregoing documents by these cautionary statements.

USE OF PROCEEDS

Except as described in any applicable prospectus supplement or in any free writing prospectuses we have authorized for use in connection with a specific offering, we currently intend to use the net proceeds from the sale of the securities offered by us hereunder, if any, for working capital and general corporate purposes, including sales and marketing expenses, research and development expenses and general and administrative expenses.

DESCRIPTION OF CAPITAL STOCK

The following description of our capital stock is not complete and may not contain all the information you should consider before investing in our capital stock. This description is summarized from, and qualified in its entirety by reference to, our amended and restated certificate of incorporation and bylaws which have been publicly filed with the SEC, including our Current Reports on Form 8-K as filed with the SEC on August 19, 2025 and October 20, 2025. See "Where You Can Find More Information" and "Incorporation by Reference."

Authorized and Outstanding Securities

Our authorized capital stock consists of 1,500,000,000 shares of common stock, $0.01 par value per share, and 5,000,000 shares of preferred stock, $0.01 par value per share, of which of which the Company has designated 15,000 shares as Series B Non-Voting Convertible Preferred Stock, 3,250 shares as Series C Non-Voting Convertible Preferred Stock, 481,250 shares as Series D Non-Voting Convertible Preferred Stock, 268,750 shares as Series E non-Voting Convertible Preferred Stock, and 1,988,283 shares of Series F Voting Retractable Preferred Stock.

As of November 24, 2025, there were 126,010,749 shares of common stock outstanding and 1,346,764 shares of preferred stock outstanding, consisting of 131 shares of Series B Non-Voting Convertible Preferred Stock, no shares of Series C Non-Voting Convertible Preferred Stock, no shares of Series D Non-Voting Convertible Preferred Stock, no shares of Series E Non-Voting Convertible Preferred Stock, and 1,346,633 shares of Series F Voting Retractable Preferred Stock.

Common Stock

Dividend rights. Subject to preferences that may apply to shares of preferred stock outstanding at the time, the holders of outstanding shares of our common stock are entitled to receive dividends out of funds legally available if our Board of Directors (the "Board"), in its discretion, determines to issue dividends and then only at the times and in the amounts that our Board may determine.

Voting rights. Each holder of common stock is entitled to one vote for each share of common stock held on all matters submitted to a vote of stockholders. Our amended and restated certificate of incorporation does not provide for the right of stockholders to cumulate votes for the election of directors. Our amended and restated certificate of incorporation establishes a classified Board, divided into three classes with staggered three-year terms. Only one class of directors is elected at each annual meeting of our stockholders, with the other classes continuing for the remainder of their respective three-year terms.

No preemptive or similar rights. Our common stock is not entitled to preemptive rights and is not subject to conversion, redemption or sinking fund provisions. The rights, preferences and privileges of the holders of our common stock are subject to, and may be adversely affected by, the rights of the holders of any series of our preferred stock that we may designate and issue in the future.

Right to receive liquidation distributions. Upon our dissolution, liquidation or winding-up, the assets legally available for distribution to holders of our common stock are distributable ratably among the holders of our common stock, subject to prior satisfaction of all outstanding debt and liabilities and the preferential rights and payment of liquidation preferences, if any, on any outstanding shares of our preferred stock.

The rights of the holders of our common stock are subject to, and may be adversely affected by, the rights of holders of shares of any preferred stock that we may designate and issue in the future.

Preferred Stock

Our Board is authorized, subject to limitations prescribed by Delaware law, to issue preferred stock in one or more series, to establish from time to time the number of shares to be included in each series and to fix the designation, powers, preferences and rights of the shares of each series and any of its qualifications, limitations or restrictions. Our Board can also increase or decrease the number of shares of any series, but not below the number of shares of that series then outstanding, without any further vote or action by our stockholders. Our Board may authorize the issuance of preferred stock with voting or conversion rights that could adversely affect the voting power or other rights of the holders of the common stock. The issuance of preferred stock, while providing flexibility in connection with financings, possible acquisitions and other corporate purposes, could, among other things, have the effect of delaying, deferring, discouraging or preventing a change in control of our company, may adversely affect the market price of our common stock and the voting and other rights of the holders of common stock, and may reduce the likelihood that common stockholders will receive dividend payments and payments upon liquidation.

We will fix the designations, voting powers, preferences and rights of the preferred stock of each series we issue under this prospectus, as well as the qualifications, limitations or restrictions thereof, in the certificate of designation relating to that series. We will file as an exhibit to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of any certificate of designation that contains the terms of the series of preferred stock we are offering. We will describe in the applicable prospectus supplement the terms of the series of preferred stock being offered, including, to the extent applicable:

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the title and stated value;

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the number of shares we are offering;

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the liquidation preference per share;

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the purchase price;

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the dividend rate, period and payment date and method of calculation for dividends;

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whether dividends will be cumulative or non-cumulative and, if cumulative, the date from which dividends will accumulate;

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the procedures for any auction and remarketing, if applicable;

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the provisions for a sinking fund, if applicable;

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the provisions for redemption or repurchase, if applicable, and any restrictions on our ability to exercise those redemption and repurchase rights;

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any listing of the preferred stock on any securities exchange or market;

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whether the preferred stock will be convertible into our common stock, and, if applicable, the conversion price, or how it will be calculated, and the conversion period;

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whether the preferred stock will be exchangeable into debt securities, and, if applicable, the exchange price, or how it will be calculated, and the exchange period;

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voting rights of the preferred stock;

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preemptive rights, if any;

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restrictions on transfer, sale or other assignment;

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whether interests in the preferred stock will be represented by depositary shares;

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a discussion of material United States federal income tax considerations applicable to the preferred stock;

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the relative ranking and preferences of the preferred stock as to dividend rights and rights if we liquidate, dissolve or wind up our affairs;

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any limitations on the issuance of any class or series of preferred stock ranking senior to or on a parity with the series of preferred stock as to dividend rights and rights if we liquidate, dissolve or wind up our affairs; and

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any other specific terms, preferences, rights or limitations of, or restrictions on, the preferred stock.

Series B Preferred Stock

Designation

The Company has designated up to 15,000 shares of its preferred stock as Series B Non-Voting Convertible Preferred Stock, par value $0.01 per share. Each share has a stated value of $1,000, which may be increased as provided in Section 3 of the Certificate of Designation.

Ranking

The Series B Preferred Stock ranks pari passu with the common stock with respect to dividends and liquidation rights.

Voting Rights

Series B Preferred Stock does not have preemptive rights and has no voting rights except as required by the Delaware General Corporation Law and in certain limited matters affecting its rights.

Conversion Rights

Each share of Series B Preferred Stock is convertible, at the option of the holder at any time, into a number of shares of common stock determined by dividing the stated value by the applicable conversion price, subject to the beneficial ownership and other limitations in the Certificate of Designation. The conversion price was initially $0.40 per share of common stock (subject to adjustment).

Dividends

Holders of Series B Preferred Stock are entitled to receive dividends on an "if-converted" basis when, as and if dividends are declared on the common stock.

Liquidation Preference

Upon a liquidation, dissolution or winding-up of the Company, holders of Series B Preferred Stock are entitled to receive the same consideration they would have received if the shares had been converted into common stock immediately prior to such event.

Transfer Restrictions

The Series B Preferred Stock may only be sold, transferred, assigned, pledged or otherwise disposed of in accordance with state and federal securities laws.

Series C Preferred Stock

Designation

The Company has designated up to 3,250 shares of its preferred stock as Series C Non-Voting Convertible Preferred Stock, par value $0.01 per share, with a stated value per share of $1,000.

Ranking

The Series C Preferred Stock ranks pari passu with the Company's common stock in respect of dividends and liquidation rights, except as otherwise provided in the Certificate of Designation.

Voting Rights

The holders of the Series C Preferred Stock do not have voting rights.

Conversion Rights

Each share of Series C Preferred Stock is convertible, at the option of the holder, into a number of shares of common stock determined by dividing the stated value by the conversion price. Conversions are subject to beneficial ownership limitations as detailed in the Certificate of Designation.

Dividends

Holders of Series C Preferred Stock are entitled to receive dividends on an "if-converted" basis: when, as and if dividends are declared on common stock, Series C holders participate on the same basis. No additional dividends are payable.

Liquidation Preference

Upon any liquidation, dissolution or winding-up of the Company, whether voluntary or involuntary, the holders of Series C Preferred Stock are entitled to receive out of the assets of the Company the same amount that a holder of common stock would receive if the Series C Preferred Stock were fully converted (disregarding any conversion limitations) into common stock, with such amounts paid pari passu with the holders of common stock. The Company is required to mail written notice of any such liquidation at least 45 days prior to the payment date stated therein to each holder of Series C Preferred Stock.

Transfer Restrictions

The Series C Preferred Stock may only be sold, transferred, assigned, pledged or otherwise disposed of in accordance with state and federal securities laws.

Series D and Series E Preferred Stock

Designation

The Company has designated 481,250 shares of its preferred stock as Series D Non-Voting Convertible Preferred Stock, par value $0.01 per share, pursuant to a Certificate of Designation filed with the Delaware Secretary of State on August 19, 2025. Company has designated 268,750 shares of its preferred stock as Series E Non-Voting Convertible Preferred Stock, par value $0.01 per share, pursuant to a Certificate of Designation filed with the Delaware Secretary of State on October 16, 2025. The powers, preferences, rights, qualifications, limitations and restrictions of the Series D Preferred Stock and Series E Preferred Stock are substantially similar, except as specifically noted below.

Ranking

The Series D Preferred Stock and Series E Preferred Stock each rank pari passu with the Company's common stock with respect to dividends and liquidation rights, except as expressly set forth in their respective certificates of designation.

Voting Rights

The Series D Preferred Stock and Series E Preferred Stock generally have no voting rights, except as required by Delaware law or as otherwise provided in their certificates of designation. The consent of the holders of a majority of the outstanding shares of the applicable series would be required to:

(i)

alter or change adversely the powers, preferences or rights of that series,

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amend the Company's certificate of incorporation or other charter documents in a manner that adversely affects the rights of that series,

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increase the number of authorized shares of that series, or

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enter into any agreement with respect to any of the foregoing.

Conversion Rights

Each share of Series D Preferred Stock and Series E Preferred Stock is convertible into 160 shares of common stock (or up to 77.0 million and 43.0 million shares, respectively, in the aggregate), subject to the beneficial-ownership and share-issuance limitations set forth in the applicable certificate of designation and to receipt of stockholder approval of the conversion proposal (the "Conversion Approval"). On the third business day after the Company receives the Conversion Approval, all outstanding shares of Series D Preferred Stock will automatically convert into shares of common stock. On the 30th business day after the Conversion Approval is received and the Series E Preferred Stock has been issued, all outstanding shares of Series E Preferred Stock will automatically convert into shares of common stock. The conversion rates of the Series D Preferred Stock and Series E Preferred Stock are subject to customary anti-dilution adjustments for stock dividends, stock splits, reverse stock splits and similar events, as set forth in their respective certificates of designation. All shares of Series D Preferred Stock and Series E Preferred Stock were converted into shares of common stock on October 21, 2025.

Dividends

Holders of Series D Preferred Stock and Series E Preferred Stock are entitled to receive dividends on an "if-converted" basis, in the same form and amount as dividends paid on the common stock, when, as and if dividends are declared on the common stock; provided, however, that no dividends will be paid prior to the declaration and payment of the special dividend and the Company's receipt of the Conversion Approval.

Liquidation Preference

Upon any liquidation, dissolution or winding-up of the Company, holders of Series D Preferred Stock and Series E Preferred Stock are entitled to receive the same consideration they would have been entitled to receive had they converted such shares into common stock immediately prior to such event.

Transfer Restrictions

The Series D Preferred Stock and Series E Preferred Stock may only be sold, transferred, assigned, pledged or otherwise disposed of in accordance with state and federal securities laws.

Series F Preferred Stock

Designation

The Company has designated 1,988,283 shares of its preferred stock as Series F Voting Retractable Preferred Stock, par value $0.01 per share.

Ranking

The Series F Preferred Stock ranks senior to the common stock with respect to voting rights but does not carry a separate liquidation preference or dividend rights senior to the common stock, except as expressly provided in the Certificate of Designation.

Voting Rights

Each share of Series F Preferred Stock is entitled to vote together with the holders of common stock, on an as-converted basis, representing in the aggregate approximately 842,832 votes, or about 12.3% of the voting power of the Company's capital stock as of the record date for the 2025 Annual Meeting of Stockholders. Pursuant to the Series F Agreements, the holders have agreed to vote all shares of Series F Preferred Stock in favor of the proposals presented at the 2025 Annual Meeting, including the conversion approval.

Retirement Rights

Following receipt of stockholder approval at the 2025 Annual Meeting of Stockholders, each holder has the right to require that the Company retire (repurchase) all shares of Series F Preferred Stock held by such holder for cash consideration of $175,000 per holder (aggregate $525,000). The Company also has the right to retire the Series F Preferred Stock for the same amount after December 31, 2025, if such shares have not previously been retired. The Series F Preferred Stock is not convertible into common stock.

Dividends

The Series F Preferred Stock does not accrue or pay dividends, except to the extent that holders are entitled to participate on an "as-converted" basis if and when dividends are declared and paid on the common stock.

Liquidation Preference

Upon any voluntary or involuntary liquidation, dissolution or winding-up of the Company, holders of Series F Preferred Stock are entitled to receive the same consideration they would have been entitled to receive had they converted such shares into common stock immediately prior to such event.

Transfer Restrictions

The Series F Preferred Stock may only be sold, transferred, assigned, pledged or otherwise disposed of in accordance with state and federal securities laws and as permitted by the Series F Agreements.

Outstanding Warrants

As of November 24, 2025, we had warrants outstanding to purchase an aggregate of 5,491,188 shares of common stock with a weighted-average exercise price of $1.61 per share.

Anti-takeover effects of provisions of our certificate of incorporation and bylaws and Delaware law

Amended and restated certificate of incorporation and bylaws. Our amended and restated certificate of incorporation provides that our Board is divided into three classes with staggered three-year terms. Only one class of directors is elected at each annual meeting of our stockholders, with the other classes continuing for the remainder of their respective three-year terms. Because holders of our common stock do not have cumulative voting rights in the election of directors, stockholders holding a majority of the shares of common stock outstanding are able to elect all of our directors. Our Board is able to elect a director to fill a vacancy created by the expansion of the Board or due to the resignation or departure of an existing board member. Our amended and restated certificate of incorporation and bylaws also provide that all stockholder actions must be effected at a duly called meeting of stockholders and not by written consent, and that only the Board pursuant to a resolution adopted by a majority of the total number of authorized directors may call a special meeting of stockholders. In addition, our bylaws include a requirement for the advance notice of nominations for election to the Board or for proposing matters that can be acted upon at a stockholders' meeting. Our amended and restated certificate of incorporation provides for the ability of the Board to issue, without stockholder approval, up to 5,000,000 shares of preferred stock with terms set by the Board, which rights could be senior to those of our common stock. The existence of authorized but undesignated preferred stock makes it possible for our Board to issue preferred stock with voting or other rights or preferences that could impede the success of any attempt to change control of our company. Our amended and restated certificate of incorporation and bylaws also provide that approval of at least 66-2/3% of the shares entitled to vote at an election of directors will be required to adopt, amend or repeal our bylaws, or repeal the provisions of our amended and restated certificate of incorporation regarding the election of directors and the inability of stockholders to take action by written consent in lieu of a meeting.

The foregoing provisions make it difficult for holders of our common stock to replace our Board. In addition, the authorization of undesignated preferred stock makes it possible for our Board to issue preferred stock with voting or other rights or preferences that could impede the success of any attempt to change control of our company.

Section 203 of the Delaware General Corporation Law

We are subject to the provisions of Section 203 of the DGCL. In general, Section 203 prohibits a publicly-held Delaware corporation from engaging in a "business combination" with an "interested stockholder" for a three-year period following the time that this stockholder becomes an interested stockholder, unless the business combination is approved in a prescribed manner. A "business combination" includes, among other things, a merger, asset or stock sale or other transaction resulting in a financial benefit to the interested stockholder. An "interested stockholder" is a person who, together with affiliates and associates, owns, or did own within three years prior to the determination of interested stockholder status, 15% or more of the corporation's voting stock.

Under Section 203, a business combination between a corporation and an interested stockholder is prohibited unless it satisfies one of the following conditions: before the stockholder became interested, our board of directors approved either the business combination or the transaction which resulted in the stockholder becoming an interested stockholder; upon consummation of the transaction which resulted in the stockholder becoming an interested stockholder, the interested stockholder owned at least 85% of the voting stock of the corporation outstanding at the time the transaction commenced, excluding for purposes of determining the voting stock outstanding, shares owned by persons who are directors and also officers, and employee stock plans, in some instances; or at or after the time the stockholder became interested, the business combination was approved by our board of directors of the corporation and authorized at an annual or special meeting of the stockholders by the affirmative vote of at least two-thirds of the outstanding voting stock which is not owned by the interested stockholder.

A Delaware corporation may "opt out" of these provisions with an express provision in its original certificate of incorporation or an express provision in its certificate of incorporation or by-laws resulting from a stockholders' amendment approved by at least a majority of the outstanding voting shares. We have not opted out of these provisions. As a result, mergers or other takeover or change in control attempts of us may be discouraged or prevented.

Transfer Agent and Registrar

Computershare Shareholder Services, Inc., located in Providence, Rhode Island, Providence County, is the transfer agent and registrar for our common stock in the United States and Computershare Investor Services, Inc., located in Toronto, Ontario, Canada, is the co-transfer agent and registrar for our common stock in Canada. The transfer agent for any series of preferred stock that we may offer under this prospectus will be named and described in the prospectus supplement related to that series.

Listing on the NYSE American

Our common stock is listed on the NYSE American under the symbol "NBY." The applicable prospectus supplement will contain information, where applicable, as to any other listing, if any, on the NYSE American or any securities market or other exchange of the preferred stock covered by such prospectus supplement.

DESCRIPTION OF DEBT SECURITIES

We may issue debt securities from time to time, in one or more series, as either senior or subordinated debt or as senior or subordinated convertible debt. While the terms we have summarized below will apply generally to any debt securities that we may offer under this prospectus, we will describe the particular terms of any debt securities that we may offer in more detail in the applicable prospectus supplement. The terms of any debt securities offered under a prospectus supplement may differ from the terms described below. Unless the context requires otherwise, whenever we refer to the indenture, we also are referring to any supplemental indentures that specify the terms of a particular series of debt securities.

We will issue the debt securities under the indenture that we will enter into with a trustee named in the indenture. The indenture will be qualified under the Trust Indenture Act of 1939, as amended (the "Trust Indenture Act"). We have filed the form of indenture as an exhibit to the registration statement of which this prospectus is a part, and supplemental indentures and forms of debt securities containing the terms of the debt securities being offered will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports that we file with the SEC.

The following summary of material provisions of the debt securities and the indenture is subject to, and qualified in its entirety by reference to, all of the provisions of the indenture applicable to a particular series of debt securities. We urge you to read the applicable prospectus supplements and any related free writing prospectuses related to the debt securities that we may offer under this prospectus, as well as the complete indenture that contains the terms of the debt securities.

General

The indenture does not limit the amount of debt securities that we may issue. It provides that we may issue debt securities up to the principal amount that we may authorize and may be in any currency or currency unit that we may designate. Except for the limitations on consolidation, merger and sale of all or substantially all of our assets contained in the indenture, the terms of the indenture do not contain any covenants or other provisions designed to give holders of any debt securities protection against changes in our operations, financial condition or transactions involving us.

We may issue the debt securities issued under the indenture as "discount securities," which means they may be sold at a discount below their stated principal amount. These debt securities, as well as other debt securities that are not issued at a discount, may be issued with "original issue discount," or OID, for U.S. federal income tax purposes because of interest payment and other characteristics or terms of the debt securities. Material U.S. federal income tax considerations applicable to debt securities issued with OID will be described in more detail in any applicable prospectus supplement.

We will describe in the applicable prospectus supplement the terms of the series of debt securities being offered, including:

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the title of the series of debt securities;

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any limit upon the aggregate principal amount that may be issued;

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the maturity date or dates;

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the form of the debt securities of the series;

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the applicability of any guarantees;

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whether or not the debt securities will be secured or unsecured, and the terms of any secured debt;

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whether the debt securities rank as senior debt, senior subordinated debt, subordinated debt or any combination thereof, and the terms of any subordination;

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if the price (expressed as a percentage of the aggregate principal amount thereof) at which such debt securities will be issued is a price other than the principal amount thereof, the portion of the principal amount thereof payable upon declaration of acceleration of the maturity thereof, or if applicable, the portion of the principal amount of such debt securities that is convertible into another security or the method by which any such portion shall be determined;

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the interest rate or rates, which may be fixed or variable, or the method for determining the rate and the date interest will begin to accrue, the dates interest will be payable and the regular record dates for interest payment dates or the method for determining such dates;

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our right, if any, to defer payment of interest and the maximum length of any such deferral period;

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if applicable, the date or dates after which, or the period or periods during which, and the price or prices at which, we may, at our option, redeem the series of debt securities pursuant to any optional or provisional redemption provisions and the terms of those redemption provisions;

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the date or dates, if any, on which, and the price or prices at which we are obligated, pursuant to any mandatory sinking fund or analogous fund provisions or otherwise, to redeem, or at the holder's option to purchase, the series of debt securities and the currency or currency unit in which the debt securities are payable;

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the denominations in which we will issue the series of debt securities, if other than denominations of $1,000 and any integral multiple thereof;

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any and all terms, if applicable, relating to any auction or remarketing of the debt securities of that series and any security for our obligations with respect to such debt securities and any other terms which may be advisable in connection with the marketing of debt securities of that series;

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whether the debt securities of the series shall be issued in whole or in part in the form of a global security or securities; the terms and conditions, if any, upon which such global security or securities may be exchanged in whole or in part for other individual securities; and the depositary for such global security or securities;

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if applicable, the provisions relating to conversion or exchange of any debt securities of the series and the terms and conditions upon which such debt securities will be so convertible or exchangeable, including the conversion or exchange price, as applicable, or how it will be calculated and may be adjusted, any mandatory or optional (at our option or the holders' option) conversion or exchange features, the applicable conversion or exchange period and the manner of settlement for any conversion or exchange;

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if other than the full principal amount thereof, the portion of the principal amount of debt securities of the series which shall be payable upon declaration of acceleration of the maturity thereof;

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any changes in or additions to the covenants applicable to the particular debt securities being issued, including, among others, the consolidation, merger or sale covenant;

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additions to or changes in the events of default with respect to the securities and any change in the right of the trustee or the holders to declare the principal, premium, if any, and interest, if any, with respect to such securities to be due and payable;

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additions to or changes in or deletions of the provisions relating to covenant defeasance and legal defeasance;

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additions to or changes in the provisions relating to satisfaction and discharge of the indenture;

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additions to or changes in the provisions relating to the modification of the indenture both with and without the consent of holders of debt securities issued under the indenture;

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the currency of payment of debt securities if other than U.S. dollars and the manner of determining the equivalent amount in U.S. dollars;

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whether interest will be payable in cash or additional debt securities at our or the holders' option and the terms and conditions upon which the election may be made;

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the terms and conditions, if any, upon which we will pay amounts in addition to the stated interest, premium, if any and principal amounts of the debt securities of the series to any holder that is not a "United States person" for federal tax purposes;

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any restrictions on transfer, sale or assignment of the debt securities of the series; and

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any other specific terms, preferences, rights or limitations of, or restrictions on, the debt securities, any other additions or changes in the provisions of the indenture, and any terms that may be required by us or advisable under applicable laws or regulations.

Conversion or Exchange Rights

We will set forth in the prospectus supplement the terms on which a series of debt securities may be convertible into or exchangeable for our common stock or our other securities. We will include provisions as to settlement upon conversion or exchange and whether conversion or exchange is mandatory, at the option of the holder or at our option. We may include provisions pursuant to which the number of shares of our common stock or our other securities that the holders of the series of debt securities receive would be subject to adjustment.

Consolidation, Merger or Sale

Unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, the indenture will not contain any covenant that restricts our ability to merge or consolidate, or sell, convey, transfer or otherwise dispose of all or substantially all of our assets. However, any successor to or acquirer of such assets must assume all of our obligations under the indenture or the debt securities, as appropriate. If the debt securities are convertible into or exchangeable for our other securities or securities of other entities, we or the person with whom we consolidate or merge or to whom we sell all of our property must make provisions for the conversion of the debt securities into securities that the holders of the debt securities would have received if they had converted the debt securities before the consolidation, merger or sale.

Events of Default Under the Indenture

Unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, the following are events of default under the indenture with respect to any series of debt securities that we may issue:

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if we fail to pay any installment of interest on any series of debt securities, as and when the same shall become due and payable, and such default continues for a period of 90 days; provided, however, that a valid extension of an interest payment period by us in accordance with the terms of any indenture supplemental thereto shall not constitute a default in the payment of interest for this purpose;

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if we fail to pay the principal of, or premium, if any, on any series of debt securities as and when the same shall become due and payable whether at maturity, upon redemption, by declaration or otherwise, or in any payment required by any sinking or analogous fund established with respect to such series; provided, however, that a valid extension of the maturity of such debt securities in accordance with the terms of any indenture supplemental thereto shall not constitute a default in the payment of principal or premium, if any;

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if we fail to observe or perform any other covenant or agreement contained in the debt securities or the indenture, other than a covenant specifically relating to another series of debt securities, and our failure continues for 90 days after we receive written notice of such failure, requiring the same to be remedied and stating that such is a notice of default thereunder, from the trustee or holders of at least 25% in aggregate principal amount of the outstanding debt securities of the applicable series; and

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if specified events of bankruptcy, insolvency or reorganization occur.

If an event of default with respect to debt securities of any series occurs and is continuing, other than an event of default specified in the last bullet point above, the trustee or the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series, by notice to us in writing, and to the trustee if notice is given by such holders, may declare the unpaid principal of, premium, if any, and accrued interest, if any, due and payable immediately. If an event of default specified in the last bullet point above occurs with respect to us, the principal amount of and accrued interest, if any, of each issue of debt securities then outstanding shall be due and payable without any notice or other action on the part of the trustee or any holder.

The holders of a majority in principal amount of the outstanding debt securities of an affected series may waive any default or event of default with respect to the series and its consequences, except defaults or events of default regarding payment of principal, premium, if any, or interest, unless we have cured the default or event of default in accordance with the indenture. Any waiver shall cure the default or event of default.

Subject to the terms of the indenture, if an event of default under an indenture shall occur and be continuing, the trustee will be under no obligation to exercise any of its rights or powers under such indenture at the request or direction of any of the holders of the applicable series of debt securities, unless such holders have offered the trustee reasonable indemnity. The holders of a majority in principal amount of the outstanding debt securities of any series will have the right to direct the time, method and place of conducting any proceeding for any remedy available to the trustee, or exercising any trust or power conferred on the trustee, with respect to the debt securities of that series, provided that:

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the direction so given by the holder is not in conflict with any law or the applicable indenture; and

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subject to its duties under the Trust Indenture Act, the trustee need not take any action that might involve it in personal liability or might be unduly prejudicial to the holders not involved in the proceeding.

A holder of the debt securities of any series will have the right to institute a proceeding under the indenture or to appoint a receiver or trustee, or to seek other remedies only if:

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the holder has given written notice to the trustee of a continuing event of default with respect to that series;

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the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series have made written request, and such holders have offered reasonable indemnity to the trustee to institute the proceeding as trustee; and

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the trustee does not institute the proceeding, and does not receive from the holders of a majority in aggregate principal amount of the outstanding debt securities of that series other conflicting directions within 90 days after the notice, request and offer.

These limitations do not apply to a suit instituted by a holder of debt securities if we default in the payment of the principal, premium, if any, or interest on, the debt securities.

We will periodically file statements with the trustee regarding our compliance with specified covenants in the indenture.

Modification of Indenture; Waiver

We and the trustee may change an indenture without the consent of any holders with respect to specific matters:

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to cure any ambiguity, defect or inconsistency in the indenture or in the debt securities of any series;

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to comply with the provisions described above under "Description of Debt Securities-Consolidation, Merger or Sale;"

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to provide for uncertificated debt securities in addition to or in place of certificated debt securities;

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to add to our covenants, restrictions, conditions or provisions such new covenants, restrictions, conditions or provisions for the benefit of the holders of all or any series of debt securities, to make the occurrence, or the occurrence and the continuance, of a default in any such additional covenants, restrictions, conditions or provisions an event of default or to surrender any right or power conferred upon us in the indenture;

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to add to, delete from or revise the conditions, limitations, and restrictions on the authorized amount, terms, or purposes of issue, authentication and delivery of debt securities, as set forth in the indenture;

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to make any change that does not adversely affect the interests of any holder of debt securities of any series in any material respect;

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to provide for the issuance of and establish the form and terms and conditions of the debt securities of any series as provided above under "Description of Debt Securities-General" to establish the form of any certifications required to be furnished pursuant to the terms of the indenture or any series of debt securities, or to add to the rights of the holders of any series of debt securities;

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to evidence and provide for the acceptance of appointment under any indenture by a successor trustee; or

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to comply with any requirements of the SEC in connection with the qualification of any indenture under the Trust Indenture Act.

In addition, under the indenture, the rights of holders of a series of debt securities may be changed by us and the trustee with the written consent of the holders of at least a majority in aggregate principal amount of the outstanding debt securities of each series that is affected. However, unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, we and the trustee may make the following changes only with the consent of each holder of any outstanding debt securities affected:

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extending the fixed maturity of any debt securities of any series;

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reducing the principal amount, reducing the rate of or extending the time of payment of interest, or reducing any premium payable upon the redemption of any series of any debt securities; or

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reducing the percentage of debt securities, the holders of which are required to consent to any amendment, supplement, modification or waiver.

Discharge

Each indenture provides that we can elect to be discharged from our obligations with respect to one or more series of debt securities, except for specified obligations, including obligations to:

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provide for payment;

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register the transfer or exchange of debt securities of the series;

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replace stolen, lost or mutilated debt securities of the series;

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pay principal of and premium and interest on any debt securities of the series;

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maintain paying agencies;

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hold monies for payment in trust;

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recover excess money held by the trustee;

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compensate and indemnify the trustee; and

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appoint any successor trustee.

In order to exercise our rights to be discharged, we must deposit with the trustee money or government obligations sufficient to pay all the principal of, any premium, if any, and interest on, the debt securities of the series on the dates payments are due.

Form, Exchange and Transfer

We will issue the debt securities of each series only in fully registered form without coupons and, unless we provide otherwise in the applicable prospectus supplement, in denominations of $1,000 and any integral multiple thereof. The indenture provides that we may issue debt securities of a series in temporary or permanent global form and as book-entry securities that will be deposited with, or on behalf of, The Depository Trust Company, or DTC, or another depositary named by us and identified in a prospectus supplement with respect to that series. To the extent the debt securities of a series are issued in global form and as book-entry, a description of terms relating will be set forth in the applicable prospectus supplement.

At the option of the holder, subject to the terms of the indenture and the limitations applicable to global securities described in the applicable prospectus supplement, the holder of the debt securities of any series can exchange the debt securities for other debt securities of the same series, in any authorized denomination and of like tenor and aggregate principal amount.

Subject to the terms of the indenture and the limitations applicable to global securities set forth in the applicable prospectus supplement, holders of the debt securities may present the debt securities for exchange or for registration of transfer, duly endorsed or with the form of transfer endorsed thereon duly executed if so required by us or the security registrar, at the office of the security registrar or at the office of any transfer agent designated by us for this purpose. Unless otherwise provided in the debt securities that the holder presents for transfer or exchange, we will impose no service charge for any registration of transfer or exchange, but we may require payment of any taxes or other governmental charges.

We will name in the applicable prospectus supplement the security registrar, and any transfer agent in addition to the security registrar, that we initially designate for any debt securities. We may at any time designate additional transfer agents or rescind the designation of any transfer agent or approve a change in the office through which any transfer agent acts, except that we will be required to maintain a transfer agent in each place of payment for the debt securities of each series.

If we elect to redeem the debt securities of any series, we will not be required to:

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issue, register the transfer of, or exchange any debt securities of that series during a period beginning at the opening of business 15 days before the day of mailing of a notice of redemption of any debt securities that may be selected for redemption and ending at the close of business on the day of the mailing; or

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register the transfer of or exchange any debt securities so selected for redemption, in whole or in part, except the unredeemed portion of any debt securities we are redeeming in part.

Information Concerning the Trustee

The trustee, other than during the occurrence and continuance of an event of default under an indenture, undertakes to perform only those duties as are specifically set forth in the applicable indenture. Upon an event of default under an indenture, the trustee must use the same degree of care as a prudent person would exercise or use in the conduct of his or her own affairs. Subject to this provision, the trustee is under no obligation to exercise any of the powers given it by the indenture at the request of any holder of debt securities unless it is offered reasonable security and indemnity against the costs, expenses and liabilities that it might incur.

Payment and Paying Agents

Unless we otherwise indicate in the applicable prospectus supplement, we will make payment of the interest on any debt securities on any interest payment date to the person in whose name the debt securities, or one or more predecessor securities, are registered at the close of business on the regular record date for the interest.

We will pay principal of and any premium and interest on the debt securities of a particular series at the office of the paying agents designated by us, except that unless we otherwise indicate in the applicable prospectus supplement, we will make interest payments by check that we will mail to the holder or by wire transfer to certain holders. Unless we otherwise indicate in the applicable prospectus supplement, we will designate the corporate trust office of the trustee as our sole paying agent for payments with respect to debt securities of each series. We will name in the applicable prospectus supplement any other paying agents that we initially designate for the debt securities of a particular series. We will maintain a paying agent in each place of payment for the debt securities of a particular series.

All money we pay to a paying agent or the trustee for the payment of the principal of or any premium or interest on any debt securities that remains unclaimed at the end of two years after such principal, premium or interest has become due and payable will be repaid to us, and the holder of the debt security thereafter may look only to us for payment thereof.

Governing Law

The indenture and the debt securities will be governed by and construed in accordance with the laws of the State of New York, except to the extent that the Trust Indenture Act of 1939 is applicable.

DESCRIPTION OF WARRANTS

The following description, together with the additional information that we include in any applicable prospectus supplement and in any related free writing prospectus that we may authorize to be distributed to you, summarizes the material terms and provisions of the warrants that we may offer under this prospectus, which may be issued in one or more series. Warrants may be offered independently or in combination with other securities offered by any prospectus supplement. While the terms we have summarized below will apply generally to any warrants that we may offer under this prospectus, we will describe the particular terms of any series of warrants in more detail in the applicable prospectus supplement. The following description of warrants will apply to the warrants offered by this prospectus unless we provide otherwise in the applicable prospectus supplement. The applicable prospectus supplement for a particular series of warrants may specify different or additional terms.

We will file as exhibits to the registration statement of which this prospectus is a part by amendment, or will incorporate by reference from reports that we file with the SEC, the form of warrant and/or the warrant agreement and warrant certificate, as applicable, that contain the terms of the particular series of warrants we are offering, and any supplemental agreements, before the issuance of such warrants. The following summaries of material terms and provisions of the warrants are subject to, and qualified in their entirety by reference to, all the provisions of the form of warrant and/or the warrant agreement and warrant certificate, as applicable, and any supplemental agreements applicable to a particular series of warrants that we may offer under this prospectus. We urge you to read the applicable prospectus supplement related to the particular series of warrants that we may offer under this prospectus, as well as any related free writing prospectuses, and the complete form of warrant and/or the warrant agreement and warrant certificate, as applicable, and any supplemental agreements, that contain the terms of the warrants.

General

We will describe in the applicable prospectus supplement the terms of the series of warrants being offered, including:

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the offering price and aggregate number of warrants offered;

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the currency for which the warrants may be purchased;

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if applicable, the designation and terms of the securities with which the warrants are issued and the number of warrants issued with each such security or each principal amount of such security;

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in the case of warrants to purchase debt securities, the principal amount of debt securities purchasable upon exercise of one warrant and the price at, and currency in which, this principal amount of debt securities may be purchased upon such exercise;

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in the case of warrants to purchase common stock or preferred stock, the number of shares of common stock or preferred stock, as the case may be, purchasable upon the exercise of one warrant and the price at which these shares may be purchased upon such exercise;

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the effect of any merger, consolidation, sale or other disposition of our business on the warrant agreements and the warrants;

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the terms of any rights to redeem or call the warrants;

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any provisions for changes to or adjustments in the exercise price or number of securities issuable upon exercise of the warrants;

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the dates on which the right to exercise the warrants will commence and expire;

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the manner in which the warrant agreements and warrants may be modified;

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a discussion of any material or special U.S. federal income tax considerations of holding or exercising the warrants;

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the terms of the securities issuable upon exercise of the warrants; and

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any other specific terms, preferences, rights or limitations of or restrictions on the warrants.

Before exercising their warrants, holders of warrants will not have any of the rights of holders of the securities purchasable upon such exercise, including:

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in the case of warrants to purchase debt securities, the right to receive payments of principal of, or premium, if any, or interest on, the debt securities purchasable upon exercise or to enforce covenants in the applicable indenture; or

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in the case of warrants to purchase common stock or preferred stock, the right to receive dividends, if any, or, payments upon our liquidation, dissolution or winding up or to exercise voting rights, if any.

Exercise of Warrants

Each warrant will entitle the holder to purchase the securities that we specify in the applicable prospectus supplement at the exercise price that we describe in the applicable prospectus supplement. The warrants may be exercised as set forth in the prospectus supplement relating to the warrants offered. Unless we otherwise specify in the applicable prospectus supplement, warrants may be exercised at any time up to the close of business on the expiration date set forth in the prospectus supplement relating to the warrants offered thereby. After the close of business on the expiration date, unexercised warrants will become void.

Upon receipt of payment and the warrant or warrant certificate, as applicable, properly completed and duly executed at the corporate trust office of the warrant agent, if any, or any other office, including ours, indicated in the prospectus supplement, we will, as soon as practicable, issue and deliver the securities purchasable upon such exercise. If less than all of the warrants (or the warrants represented by such warrant certificate) are exercised, a new warrant or a new warrant certificate, as applicable, will be issued for the remaining warrants.

Governing Law

Unless we otherwise specify in the applicable prospectus supplement, the warrants and any warrant agreements will be governed by and construed in accordance with the laws of the State of New York.

Enforceability of Rights by Holders of Warrants

Each warrant agent, if any, will act solely as our agent under the applicable warrant agreement and will not assume any obligation or relationship of agency or trust with any holder of any warrant. A single bank or trust company may act as warrant agent for more than one issue of warrants. A warrant agent will have no duty or responsibility in case of any default by us under the applicable warrant agreement or warrant, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a warrant may, without the consent of the related warrant agent or the holder of any other warrant, enforce by appropriate legal action its right to exercise, and receive the securities purchasable upon exercise of, its warrants.

DESCRIPTION OF UNITS

In this section, we describe the general terms and provisions of the units that we may offer. We may issue units consisting of any combination of the other types of securities offered hereunder and described in this prospectus in one or more series. Each unit will be issued so that the holder of the unit also is the holder of each security included in the unit. Thus, the holder of a unit will have the rights and obligations of a holder of each included security. We may evidence each series of units by unit certificates that we will issue under a separate agreement. We may enter into unit agreements with a unit agent. Each unit agent will be a bank or trust company that we select. We will indicate the name and address of the unit agent in the applicable prospectus supplement relating to a particular series of units.

The following description, together with the additional information included in any applicable prospectus supplement, will summarize the general features of the units that we may offer hereunder. You should read any prospectus supplement and any free writing prospectus that we may authorize to be provided to you related to the series of units being offered, as well as the complete unit agreements that contain the terms of the units. Specific unit agreements will contain additional important terms and provisions and we will file as an exhibit to the registration statement of which this prospectus is a part, or will incorporate by reference from another report that we file with the SEC, the form of each unit agreement relating to units offered under this prospectus. We urge you to read the applicable unit agreement and the applicable prospectus supplement and any other offering material in their entirety.

If we offer any units, certain terms of that series of units will be described in the applicable prospectus supplement, including, without limitation, the following, as applicable:

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the title of the series of units;

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identification and description of the separate constituent securities comprising the units;

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the price or prices at which the units will be issued;

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the date, if any, on and after which the constituent securities comprising the units will be separately transferable;

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whether the units will be issued in fully registered or global form;

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a description of the terms of any unit agreement governing the units;

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a description of the provisions for the issuance, payment, settlement, transfer or exchange of the units or the securities comprising those units;

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a discussion of certain United States federal income tax considerations applicable to the units; and

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any other terms of the units and their constituent securities.

LEGAL OWNERSHIP OF SECURITIES

We can issue securities in registered form or in the form of one or more global securities. We describe global securities in greater detail below. We refer to those persons who have securities registered in their own names on the books that we or any applicable trustee, depositary or warrant agent maintain for this purpose as the "holders" of those securities. These persons are the legal holders of the securities. We refer to those persons who, indirectly through others, own beneficial interests in securities that are not registered in their own names, as "indirect holders" of those securities. As we discuss below, indirect holders are not legal holders, and investors in securities issued in book-entry form or in street name will be indirect holders.

Book-Entry Holders

We may issue securities in book-entry form only, as we will specify in the applicable prospectus supplement. This means securities may be represented by one or more global securities registered in the name of a financial institution that holds them as depositary on behalf of other financial institutions that participate in the depositary's book-entry system. These participating institutions, which are referred to as participants, in turn, hold beneficial interests in the securities on behalf of themselves or their customers.

Only the person in whose name a security is registered is recognized as the holder of that security. Securities issued in global form will be registered in the name of the depositary or its participants. Consequently, for securities issued in global form, we will recognize only the depositary as the holder of the securities, and we will make all payments on the securities to the depositary. The depositary passes along the payments it receives to its participants, which in turn pass the payments along to their customers who are the beneficial owners. The depositary and its participants do so under agreements they have made with one another or with their customers; they are not obligated to do so under the terms of the securities.

As a result, investors in a book-entry security will not own securities directly. Instead, they will own beneficial interests in a global security, through a bank, broker or other financial institution that participates in the depositary's book-entry system or holds an interest through a participant. As long as the securities are issued in global form, investors will be indirect holders, and not holders, of the securities.

Street Name Holders

We may terminate a global security or issue securities in non-global form. In these cases, investors may choose to hold their securities in their own names or in "street name." Securities held by an investor in street name would be registered in the name of a bank, broker or other financial institution that the investor chooses, and the investor would hold only a beneficial interest in those securities through an account he or she maintains at that institution.

For securities held in street name, we will recognize only the intermediary banks, brokers and other financial institutions in whose names the securities are registered as the holders of those securities, and we will make all payments on those securities to them. These institutions pass along the payments they receive to their customers who are the beneficial owners, but only because they agree to do so in their customer agreements or because they are legally required to do so. Investors who hold securities in street name will be indirect holders, not holders, of those securities.

Legal Holders

Our obligations, as well as the obligations of any applicable trustee and of any third parties employed by us or a trustee, run only to the legal holders of the securities. We do not have obligations to investors who hold beneficial interests in global securities, in street name or by any other indirect means. This will be the case whether an investor chooses to be an indirect holder of a security or has no choice because we are issuing the securities only in global form.

For example, once we make a payment or give a notice to the holder, we have no further responsibility for the payment or notice even if that holder is required, under agreements with depositary participants or customers or by law, to pass it along to the indirect holders but does not do so. Similarly, we may want to obtain the approval of the holders to amend an indenture, to relieve us of the consequences of a default or of our obligation to comply with a particular provision of the indenture or for other purposes. In such an event, we would seek approval only from the holders, and not the indirect holders, of the securities. Whether and how the holders contact the indirect holders is up to the holders.

Special Considerations For Indirect Holders

If you hold securities through a bank, broker or other financial institution, either in book-entry form or in street name, you should check with your own institution to find out:

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the performance of third party service providers;

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how it handles securities payments and notices;

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whether it imposes fees or charges;

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how it would handle a request for the holders' consent, if ever required;

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whether and how you can instruct it to send you securities registered in your own name so you can be a holder, if that is permitted in the future;

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how it would exercise rights under the securities if there were a default or other event triggering the need for holders to act to protect their interests; and

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if the securities are in book-entry form, how the depositary's rules and procedures will affect these matters.

Global Securities

A global security is a security that represents one or any other number of individual securities held by a depositary. Generally, all securities represented by the same global securities will have the same terms.

Each security issued in book-entry form will be represented by a global security that we deposit with and register in the name of a financial institution or its nominee that we select. The financial institution that we select for this purpose is called the depositary. Unless we specify otherwise in the applicable prospectus supplement, DTC will be the depositary for all securities issued in book-entry form.

A global security may not be transferred to or registered in the name of anyone other than the depositary, its nominee or a successor depositary, unless special termination situations arise. We describe those situations below under the section entitled "Special Situations When a Global Security Will Be Terminated" in this prospectus. As a result of these arrangements, the depositary, or its nominee, will be the sole registered owner and holder of all securities represented by a global security, and investors will be permitted to own only beneficial interests in a global security. Beneficial interests must be held by means of an account with a broker, bank or other financial institution that in turn has an account with the depositary or with another institution that does. Thus, an investor whose security is represented by a global security will not be a holder of the security, but only an indirect holder of a beneficial interest in the global security.

If the prospectus supplement for a particular security indicates that the security will be issued in global form only, then the security will be represented by a global security at all times unless and until the global security is terminated. If termination occurs, we may issue the securities through another book-entry clearing system or decide that the securities may no longer be held through any book-entry clearing system.

Special Considerations For Global Securities

The rights of an indirect holder relating to a global security will be governed by the account rules of the investor's financial institution and of the depositary, as well as general laws relating to securities transfers. We do not recognize an indirect holder as a holder of securities and instead deal only with the depositary that holds the global security.

If securities are issued only in the form of a global security, an investor should be aware of the following:

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an investor cannot cause the securities to be registered in his or her name, and cannot obtain non-global certificates for his or her interest in the securities, except in the special situations we describe below;

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an investor will be an indirect holder and must look to his or her own bank or broker for payments on the securities and protection of his or her legal rights relating to the securities, as we describe above;

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an investor may not be able to sell interests in the securities to some insurance companies and to other institutions that are required by law to own their securities in non-book-entry form;

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an investor may not be able to pledge his or her interest in a global security in circumstances where certificates representing the securities must be delivered to the lender or other beneficiary of the pledge in order for the pledge to be effective;

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the depositary's policies, which may change from time to time, will govern payments, transfers, exchanges and other matters relating to an investor's interest in a global security;

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we and any applicable trustee have no responsibility for any aspect of the depositary's actions or for its records of ownership interests in a global security, nor do we or any applicable trustee supervise the depositary in any way;

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the depositary may, and we understand that DTC will, require that those who purchase and sell interests in a global security within its book-entry system use immediately available funds, and your broker or bank may require you to do so as well; and

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financial institutions that participate in the depositary's book-entry system, and through which an investor holds its interest in a global security, may also have their own policies affecting payments, notices and other matters relating to the securities.

There may be more than one financial intermediary in the chain of ownership for an investor. We do not monitor and are not responsible for the actions of any of those intermediaries.

Special Situations When a Global Security Will Be Terminated

In a few special situations described below, the global security will terminate and interests in it will be exchanged for physical certificates representing those interests. After that exchange, the choice of whether to hold securities directly or in street name will be up to the investor. Investors must consult their own banks or brokers to find out how to have their interests in securities transferred to their own name, so that they will be direct holders. We have described the rights of holders and street name investors above.

Unless we provide otherwise in the applicable prospectus supplement, the global security will terminate when the following special situations occur:

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if the depositary notifies us that it is unwilling, unable or no longer qualified to continue as depositary for that global security and we do not appoint another institution to act as depositary within 90 days;

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if we notify any applicable trustee that we wish to terminate that global security; or

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if an event of default has occurred with regard to securities represented by that global security and has not been cured or waived.

The applicable prospectus supplement may also list additional situations for terminating a global security that would apply only to the particular series of securities covered by the applicable prospectus supplement. When a global security terminates, the depositary, and not we or any applicable trustee, is responsible for deciding the names of the institutions that will be the initial direct holders.

PLAN OF DISTRIBUTION

We may sell the securities from time to time pursuant to underwritten public offerings, direct sales to the public, negotiated transactions, block trades or a combination of these methods. We may sell the securities to or through underwriters or dealers, through agents, directly to one or more purchasers or through a combination of any of these methods. We may distribute securities from time to time in one or more transactions:

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at a fixed price or prices, which may be changed;

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at market prices prevailing at the time of sale;

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at prices related to such prevailing market prices; or

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at negotiated prices.

Each time we use this prospectus to sell our securities, we will also provide a prospectus supplement. A prospectus supplement or supplements (and any related free writing prospectus that we may authorize to be provided to you) will describe the specific plan of distribution and terms of the offering of the securities, including, to the extent applicable:

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the name or names of the underwriters, dealers or agents, if any, and the amounts of securities underwritten or purchased by each of them;

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the purchase price of the securities or other consideration therefor, and the proceeds, if any, we will receive from the sale;

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any over-allotment options under which underwriters may purchase additional securities from us;

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any agency fees or underwriting discounts and other items constituting agents' or underwriters' compensation;

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any public offering price;

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any discounts or concessions allowed or reallowed or paid to dealers; and

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any securities exchange or market on which the securities may be listed.

Only underwriters, dealers or agents named in the prospectus supplement will be underwriters, dealers or agents of the securities offered by the prospectus supplement.

If underwriters are used in the sale, they will acquire the securities for their own account, and may resell the securities from time to time in one or more transactions at a fixed public offering price or at varying prices determined at the time of sale. The obligations of the underwriters to purchase the securities will be subject to the conditions set forth in the applicable underwriting agreement. We may offer the securities to the public through underwriting syndicates represented by managing underwriters or by underwriters without a syndicate. Subject to certain conditions, the underwriters will be obligated to purchase all of the securities offered by the prospectus supplement, other than securities covered by any over-allotment option. Any public offering price and any discounts or concessions allowed or reallowed or paid to dealers may change from time to time. We may use underwriters with whom we have a material relationship. If so, we will name the underwriter and describe the nature of any such relationship in the prospectus supplement.

We may sell securities directly or through agents we designate from time to time. We will name any agent involved in the offering and sale of securities and we will describe any commissions we will pay the agent in the prospectus supplement. If we use agents, they may then resell the securities to the public at varying prices to be determined by such agents at the time of resale. Unless the prospectus supplement states otherwise, our agent will act on a best-efforts basis for the period of its appointment. If we sell securities directly, then we may solicit offers to purchase the securities directly, and we may sell the securities directly to institutional or other investors, who may be deemed underwriters within the meaning of the Securities Act with respect to any resales of those securities. Unless otherwise indicated in a prospectus supplement, if we sell directly, no underwriters, dealers or agents would be involved. We will not make an offer of securities in any jurisdiction that does not permit such an offer. The terms of these sales will be described in the applicable prospectus supplement.

We may authorize agents or underwriters to solicit offers by certain types of institutional investors to purchase securities from us at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. Such institutions could include banks, insurance companies, pension funds, investment companies and educational and charitable institutions. We will describe the conditions to these contracts and the commissions we must pay for solicitation of these contracts in the prospectus supplement.

We may provide agents and underwriters with indemnification against civil liabilities, including liabilities under the Securities Act, or contribution with respect to payments that the agents or underwriters may make with respect to these liabilities. Agents and underwriters may engage in transactions with, or perform services for, us in the ordinary course of business.

All securities we may offer, other than common stock, will be new issues of securities with no established trading market. Any underwriters may make a market in these securities, but will not be obligated to do so and may discontinue any market making at any time without notice. We cannot guarantee the liquidity of the trading markets for any securities.

We may grant underwriters who participate in the distribution of securities an option to purchase additional securities to cover overallotments, if any, in connection with the distribution. Any underwriter may engage in over-allotment, stabilizing transactions, short-covering transactions and penalty bids in accordance with Regulation M under the Exchange Act. Over-allotment involves sales in excess of the offering size, which create a short position. Stabilizing transactions permit bids to purchase the underlying security so long as the stabilizing bids do not exceed a specified maximum price. Syndicate-covering or other short-covering transactions involve purchases of the securities, either through exercise of the over-allotment option or in the open market after the distribution is completed, to cover short positions. Penalty bids permit the underwriters to reclaim a selling concession from a dealer when the securities originally sold by the dealer are purchased in a stabilizing or covering transaction to cover short positions. Those activities may cause the price of the securities to be higher than it would otherwise be. If commenced, the underwriters may discontinue any of the activities at any time.

Unless otherwise mandated by order or other action taken by the SEC, any underwriters or agents that are qualified market makers on the NYSE American may engage in passive market making transactions in the common stock on the NYSE American in accordance with Regulation M under the Exchange Act, during the business day prior to the pricing of the offering, before the commencement of offers or sales of the common stock. Passive market makers must comply with applicable volume and price limitations and must be identified as passive market makers. In general, a passive market maker must display its bid at a price not in excess of the highest independent bid for such security; if all independent bids are lowered below the passive market maker's bid, however, the passive market maker's bid must then be lowered when certain purchase limits are exceeded. Passive market making may stabilize the market price of the securities at a level above that which might otherwise prevail in the open market and, if commenced, may be discontinued at any time.

In compliance with guidelines of the Financial Industry Regulatory Authority, or FINRA, the aggregate maximum consideration, discount or agency fees or other items constituting underwriting compensation to be received by any FINRA member or independent broker dealer may not exceed 8% of the aggregate amount of the securities offered pursuant to this prospectus and any applicable prospectus supplement or pricing supplement, as the case may be.

LEGAL MATTERS

Certain legal matters with respect to the validity of the issuance of the securities offered hereby will be passed upon by Ropes & Gray LLP, unless otherwise indicated in the applicable prospectus supplement. If the securities are being distributed in an underwritten offering, the validity of the securities will be passed upon for the underwriters by counsel identified in the applicable prospectus supplement.

EXPERTS

The consolidated financial statements of NovaBay appearing in its Annual Report on Form 10-K for the year ended December 31, 2024, and incorporated in this prospectus by reference, have been audited by WithumSmith+Brown, PC, an independent registered public accounting firm, as set forth in their report thereon, and incorporated herein by reference. Such consolidated financial statements are incorporated herein by reference in reliance upon such report given on the authority of such firm as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

We are subject to the reporting requirements of the Exchange Act and file annual, quarterly and current reports, proxy statements and other information with the SEC. The SEC maintains an internet site that contains reports, proxy and information statement, and other information regarding issuers that file electronically with the SEC, which are available at the SEC's website at http://www.sec.gov.

This prospectus is part of a registration statement on Form S-3 that we have filed with the SEC under the Securities Act and therefore omits certain information contained in the registration statement. We have also filed exhibits and schedules with the registration statement that are excluded from this prospectus, and you should refer to the applicable exhibit or schedule for a complete description of any statement referring to any contract or other document. You may obtain a copy of the registration statement, including the exhibits and schedules, without charge, at www.sec.gov.

We also maintain a website at http://www.novabay.com, through which you can access our SEC filings free of charge. The information set forth on our website is not incorporated into or otherwise part of this prospectus.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

The SEC allows us to "incorporate by reference" the information we file with the SEC. This permits us to disclose important information to you by referring to these filed documents. Any information referred to in this way is considered part of this prospectus. The information incorporated by reference is an important part of this prospectus, and information that we file later with the SEC will automatically update and supersede this information. This prospectus omits certain information contained in the registration statement, as permitted by the SEC. You should refer to the registration statement, including the exhibits, for further information about us and the securities we may offer pursuant to this prospectus. Statements in this prospectus regarding the provisions of certain documents filed with, or incorporated by reference in, the registration statement are not necessarily complete and each statement is qualified in all respects by that reference. We incorporate by reference the following documents that have been filed with the SEC (other than information that has been "furnished" but not "filed" under the Exchange Act, including, but not limited to, information furnished under either Item 2.02 or Item 7.01 of any Current Report on Form 8-K and corresponding information furnished under Item 9.01 as an exhibit thereto):

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our Annual Report on Form 10-K for the year ended December 31, 2024, as filed with the SEC on April 2, 2025;

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our Quarterly Reports on Form 10-Q for the periods ended March 31, 2025, June 30, 2025 and September 30, 2025, as filed with the SEC on May 15, 2025, August 14, 2025 and November 7, 2025, respectively;

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our Current Reports on Form 8-K, as filed with the SEC on January 10, 2025; January 22, 2025; January 23, 2025; February 4, 2025; March 11, 2025; April 22, 2025; August 19, 2025, August 26, 2025, October 9, 2025, October 20, 2025, October 21, 2025 and October 22, 2025; and

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the description of our common stock provided in Exhibit 4.1 of our Annual Report on Form 10-K for the year ended December 31, 2024, as filed with the SEC on April 2, 2025.

Any information in any of the foregoing documents will automatically be deemed to be modified or superseded to the extent that information in this prospectus modifies or replaces such information. We also incorporate by reference any future filings (other than current reports furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed on such form that are related to such items) made with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act prior to the termination of the offering of the securities made by this prospectus, including those made after the date of the initial filing of the registration statement of which this prospectus is a part and prior to effectiveness of such registration statement. Information in such future filings shall update and supplement the information provided in this prospectus as of the respective dates such information is filed. Any statements in any such future filings will automatically be deemed to modify and supersede any information in any document we previously filed with the SEC that is incorporated or deemed to be incorporated herein by reference to the extent that statements in the later filed document modify or replace such earlier statements.

We will provide, upon written or oral request, without charge to each person, including any beneficial owner, to whom a copy of this prospectus is delivered, a copy of any or all of the information incorporated herein by reference (exclusive of exhibits to such documents unless such exhibits are specifically incorporated by reference herein). You may request in writing or orally a copy of these filings, at no cost, by writing or telephoning us at the following address:

NovaBay Pharmaceuticals, Inc.

2000 Powell Street, Suite 1550

Emeryville, CA 94608

(510) 899-8838

Attn: Corporate Secretary

$100,000,000

NOVABAY PHARMACEUTICALS, INC.

Common Stock

PROSPECTUS SUPPLEMENT

January 20, 2026