Health officials say 47 people have been poisoned by toxic mushrooms since November, with deaths, liver transplants and hospitalizations reported statewide.
WASHINGTON — California health officials are warning of an unprecedented outbreak of deadly wild mushroom poisonings that has become the largest known incident of its kind in U.S. history, NBC News reported.
The California Department of Public Health and the California Poison Control System said 47 cases linked to toxic mushrooms containing amatoxins have been reported since November 2025. Four people have died, at least four others have required liver transplants and 43 people have been hospitalized, according to NBC News and state health officials.
Officials said the poisonings far exceed the fewer than five amatoxin poisoning cases typically reported in California each year.
The outbreak has been tied primarily to Death Cap and Western Destroying Angel mushrooms, two highly toxic varieties that can resemble edible mushrooms at different stages of growth. Health officials said recent spring rains and unusual environmental conditions likely contributed to the mushrooms continuing to bloom later into the season than normal.
Cases have been reported across 12 California counties stretching from Humboldt County to San Luis Obispo County and east to Sacramento and Yuba counties. Officials said the mushrooms have been found in neighborhoods, parks, nature preserves and at least one national park.
The affected patients range in age from 19 months to 84 years old, according to the advisory. Officials said those impacted speak multiple languages, including Spanish, Mandarin Chinese, Russian, Ukrainian and Indigenous languages such as Mam and Mixteco, prompting multilingual outreach campaigns.
Health officials are urging people not to forage for or eat wild mushrooms during the current high-risk period.
“Treatment is more difficult once symptoms start,” the advisory said, warning people to seek medical attention immediately if they suspect exposure.
Symptoms of amatoxin poisoning can include severe gastrointestinal illness and liver damage. Officials said the toxins are not removed by cooking, boiling or drying mushrooms.
The advisory also warned pet owners to keep animals away from wild mushrooms after several dog deaths linked to amatoxin poisoning during the outbreak.
Healthcare providers are being urged to consider mushroom poisoning in patients with gastrointestinal symptoms or elevated liver enzymes and to ask whether they recently consumed foraged mushrooms.
The outbreak remains ongoing, with state officials saying eight new cases were reported in the past four weeks, including four in the last week alone.