San Mateo County Health Warns Public About Deadly Wild Mushroom Poisoning

San Mateo County Health is warning residents about the serious and potentially deadly risks of eating wild, foraged mushrooms following the illness of a San Mateo County resident linked to death cap mushroom poisoning.

Recent rain has contributed to the widespread growth of death cap mushrooms in California. The California Department of Public Health (CDPH) advises the public to avoid picking and eating wild mushrooms during this high-risk season. Death cap mushrooms, which are currently widespread in parts of Northern California and the Central Coast, contain amatoxins that can cause severe liver damage and death. These mushrooms are often found near trees such as oaks and pines and can be easily mistaken for edible varieties and also pose a risk to pets that may ingest them while outdoors.

"Death cap mushrooms are extremely dangerous and can be mistaken for mushrooms that look safe to eat. No amount of cooking, boiling or drying makes these mushrooms safe," said Dr. Kismet Baldwin-Santana, San Mateo County Health Officer. "We recognize that mushroom hunting is a valued activity. However, the safest choice right now is to avoid eating any wild mushrooms. Even experienced foragers should exercise extreme caution and should not rely on AI-assisted field identification to distinguish between safe and poisonous mushrooms."

Amatoxin poisoning from accidental consumption of toxic mushrooms has resulted in unprecedented numbers of serious illnesses and deaths in the state. The California Department of Public Health and the California Poison Control System report three adult fatalities and three liver transplants between Nov. 18, 2025 and Jan. 6, 2026. Thirty-five cases were identified across Northern California and the Central Coast, ranging from Sonoma to San Luis Obispo. In a typical year, fewer than five cases are reported.

Symptoms of death cap mushroom poisoning can begin six to 24 hours after eating the mushrooms and may include watery diarrhea, nausea, vomiting, abdominal pain and dehydration. Symptoms may briefly improve before severe liver failure develops one to four days later.

CDPH strongly advises residents to only consume mushrooms purchased from reputable stores or known commercial sources and to avoid all wild mushrooms foraging during this season.

Anyone who may have eaten a wild mushroom or is experiencing symptoms should seek medical care immediately. The California Poison Control is available 24 hours a day to provide expert guidance at 1-800-222-1222.

For the latest information and safety guidance, residents are encouraged to follow updates from the California Department of Public Health. The agency has released statewide data linking death cap mushrooms to three deaths, three liver transplants and 35 hospitalizations.

Faizus Amin
Public Information Officer
San Mateo County Health
Press Contact: 650-867-1661
Press Email: [email protected]