Underutilization of Influenza (Flu) Treatment Drugs

Although the U.S. flu season is winding down, flu activity remains elevated and people are continuing to get sick. Prescription antiviral drugs that can treat flu in children, adults, and pregnant women are available, but those drugs are under-used. Two recent studies found that even patients with flu who are at higher risk of developing severe flu complications are not always being prescribed antiviral drugs as recommended. CDC recommends that people who are very sick with flu (for example, hospitalized) be treated with influenza antiviral medications as soon as possible. CDC likewise recommends that people with suspected or confirmed flu who are not hospitalized but are at higher risk of getting very sick from flu also receive influenza antiviral treatment as soon as possible. The recommendations also allow otherwise healthy people, including children, who have the flu to receive antiviral treatment to shorten the duration of their illness and decrease the risk for some complications.

The Data

A study in Pediatrics found that, from December 2016 through March 2020, only about half of children hospitalized with flu were treated with antivirals. A report in the Morbidity and Mortality Weekly Report (MMWR) found that use of antivirals in children with flu peaked at "70%-86% during the 2017-2018 season." Both reports show a steep drop in flu antiviral use during the COVID-19 pandemic followed by slight increases during subsequent seasons. Together, they show that flu antiviral use in children hospitalized with flu remained roughly 20% lower during the 2022-2023 and 2023-2024 seasons compared to levels before the COVID-19 pandemic.

CDC recommends that influenza antiviral treatment be started as soon as possible because the medications work better when given earlier in the course of illness, ideally within the first 2 days after symptoms begin.

Recommended Influenza Antiviral Drugs

Four influenza antiviral drugs are recommended for use in the United States:

• Oseltamivir (Tamiflu and generic)
• Peramivir (Rapivab)
• Zanamivir (Relenza)
• Baloxavir (Xofluza)

Three of these (oseltamivir, peramivir, zanamivir) are neuraminidase inhibitors that block the viral neuraminidase protein and have activity against both influenza A and B viruses. The fourth, baloxavir, is a cap-dependent endonuclease inhibitor that interferes with viral RNA transcription and blocks virus replication. Like the others, baloxavir is active against both influenza A and B viruses, but it works better against influenza B than oseltamivir.

Safety Data

With a long history of safe use, oseltamivir is the default option for most patients with flu. It is recommended for all ages, simple to administer, and available in a generic formulation. Oseltamivir slightly increases nausea and vomiting in adults and vomiting in children. These gastrointestinal side effects may be reduced by taking oseltamivir with food and are only present for the first 2 days of treatment. Beyond oseltamivir, selecting an antiviral for treatment of flu depends mainly on patient age and condition, though product availability and cost may be considerations. For more information, see Antiviral Medications Recommended for Treatment and Chemoprophylaxis of Influenza.

Other Information Sources:

Influenza Antiviral Medications: Summary for Clinicians | Influenza (Flu) | CDC

Underutilization of Influenza Antiviral Treatment Among Children and Adolescents at Higher Risk for Influenza-Associated Complications - United States, 2023-2024 | MMWR

Frutos AM, Ahmad HM, Ujamaa D, et al. Underutilization of Influenza Antiviral Treatment Among Children and Adolescents at Higher Risk for Influenza-Associated Complications - United States, 2023-2024. MMWR Morb Mortal Wkly Rep 2024;73:1022-1029. DOI: http://dx.doi.org/10.15585/mmwr.mm7345a2.

Influenza Antiviral Use in Hospitalized Children Before and During the COVID-19 Pandemic | Pediatrics | American Academy of Pediatrics

Olla Hamdan, Justin Z. Amarin, James W. Antoon, Tess Stopczynski, Laura S. Stewart, Eileen J. Klein, Janet A. Englund, Geoffrey A. Weinberg, Peter G. Szilagyi, John V. Williams, Marian G. Michaels, Julie A. Boom, Leila C. Sahni, Mary Allen Staat, Elizabeth P. Schlaudecker, Jennifer E. Schuster, Rangaraj Selvarangan, Ariana P. Toepfer, Heidi L. Moline, James D. Chappell, Andrew J. Spieker, Samantha M. Olson, Natasha B. Halasa; Influenza Antiviral Use in Hospitalized Children Before and During the COVID-19 Pandemic. Pediatrics February 2026; 157 (2): e2025071898. http://dx.doi.org/10.1542/peds.2025-071898

Ison MG, Portsmouth S, Yoshida Y, et al. Early treatment with baloxavir marboxil in high-risk adolescent and adult outpatients with uncomplicated influenza (CAPSTONE-2): a randomised, placebo-controlled, phase 3 trial. Lancet Infect Dis. 2020;20(10):1204-1214. https://doi.org/10.1016/S1473-3099(20)30004-9 .

Aoki FY, Macleod MD, Paggiaro P, Carewicz O, El Sawy A, Wat C, Griffiths M, Waalberg E, Ward P; IMPACT Study Group. Early administration of oral oseltamivir increases the benefits of influenza treatment. J Antimicrob Chemother. 2003 Jan;51(1):123-9. doi: 10.1093/jac/dkg007. PMID: 12493796.

Dobson J, Whitley RJ, Pocock S, Monto AS. Oseltamivir treatment for influenza in adults: a meta-analysis of randomised controlled trials. Lancet. 2015 May 2;385(9979):1729-1737. doi: 10.1016/S0140-6736(14)62449-1. Epub 2015 Jan 30. Erratum in: Lancet. 2015 May 2;385(9979):1728. doi: 10.1016/S0140-6736(15)60892-3. Erratum in: Lancet. 2015 May 2;385(9979):1728. doi: 10.1016/S0140-6736(15)60893-5. PMID: 25640810.

Hayden FG, Treanor JJ, Fritz RS, Lobo M, Betts RF, Miller M, Kinnersley N, Mills RG, Ward P, Straus SE. Use of the oral neuraminidase inhibitor oseltamivir in experimental human influenza: randomized controlled trials for prevention and treatment. JAMA. 1999 Oct 6;282(13):1240-6. doi: 10.1001/jama.282.13.1240. PMID: 10517426.

Malosh RE, Martin ET, Heikkinen T, Brooks WA, Whitley RJ, Monto AS. Efficacy and Safety of Oseltamivir in Children: Systematic Review and Individual Patient Data Meta-analysis of Randomized Controlled Trials. Clin Infect Dis. 2018 May 2;66(10):1492-1500. doi: 10.1093/cid/cix1040. PMID: 29186364.