California Health Officials Warn of Unprecedented Deadly Mushroom Outbreak

Forty-seven hospitalizations and four deaths have been linked to toxic foraged mushrooms as officials warn the statewide outbreak remains ongoing.

Kelly McBride Ni

Published: 5/19/2026, 7:58:44 AM EDT

California Health Officials Warn of Unprecedented Deadly Mushroom Outbreak — Death Cap mushrooms in a file photo. (CDPH via AP)

California health officials say 47 people have been hospitalized, four have died, and four have required liver transplants in an ongoing outbreak of toxic wild mushroom poisonings spreading across at least 12 counties, according to the California Poison Control System.

The outbreak, first identified in November 2025, remains active into May 2026, with eight additional cases reported in the past three weeks. Officials say exposures are tied to foraged mushrooms in multiple regions, including Napa and Monterey counties, and warn that more cases are likely.

Dr. Craig Smollin, professor of emergency medicine at UCSF Medical Center and medical director of the San Francisco Division of the California Poison Control System, said the outbreak's severity is significant.

“Since November 2025, 47 people have been hospitalized because of eating foraged wild mushrooms,” Smollin said in a California Poison Control System advisory. “Overall, four of the patients developed severe liver failure and required liver transplants. Sadly, four other patients have died. The patients range in age from 19 months to 56 years old.”

Officials said recent spring rainfall likely contributed to an increase in wild mushroom growth, raising the risk of accidental ingestion statewide in both rural and urban areas.

The California Poison Control System said the outbreak is primarily linked to Amanita phalloides, known as the death cap, and Amanita ocreata, called the destroying angel. Both contain amatoxins, potent toxins that can cause severe liver failure and death, even in small amounts.

Napa County public health officials confirmed three recent hospitalizations tied to foraging in the Deer Park area and warned that toxic mushrooms can grow anywhere, not just in forests.

“California is experiencing an unprecedented outbreak of severe illness and deaths associated with the consumption of wild mushrooms,” Napa County public health officials said.

State health agencies said cases have been reported from Humboldt and Napa to San Luis Obispo and Sacramento counties, underscoring the statewide spread.

Symptoms of amatoxin poisoning typically include severe abdominal pain, vomiting, and diarrhea, often followed by liver damage. Officials warned symptoms may be delayed six to 24 hours after ingestion, complicating early detection and treatment.

“Treatment is more difficult once symptoms start,” the California Poison Control System advisory said, urging immediate medical attention after suspected exposure.

Fatal Identification Errors

Health officials emphasized that cooking, boiling, freezing, or drying wild mushrooms does not eliminate toxins, and even experienced foragers can mistake deadly varieties for safe species. Officials strongly advised against eating mushrooms gathered by friends or family, since identification errors are common and can have fatal consequences.

Parents are urged to supervise children outdoors in areas where wild mushrooms may grow, especially after rainfall. Pet owners are also warned to keep animals away from wild mushrooms.

The California Department of Public Health has expanded multilingual outreach and launched a live outbreak dashboard, noting that patients include speakers of Spanish, Mandarin, Russian, Ukrainian, and indigenous languages such as Mam and Mixteco.

Health officials continue to recommend avoiding wild mushrooms entirely and purchasing cultivated mushrooms from grocery stores or markets.