Danger from Wild Mushrooms: What Learners Should Know

An outbreak of amatoxin poisoning has affected parts of California, with thirty-five reported cases and three deaths from November 18 to January 5. Several counties in the Bay Area and central coast, including Monterey, San Francisco, Sonoma, and Santa Cruz, have reported hospitalizations, and the number of cases far exceeds the state’s typical annual total of fewer than five. Early rains and a mild fall contributed to abundant mushroom growth in many parks and woodlands.

The primary suspect is the death cap mushroom, Amanita phalloides, which is highly toxic yet can resemble edible species that foragers know. Toxins in these mushrooms are not destroyed by cooking, boiling, drying, or freezing, and initial gastrointestinal symptoms typically begin six to twenty-four hours after ingestion. Patients may experience a deceptive recovery of their stomach symptoms while hepatocellular injury progresses, often leading to severe liver damage within forty-eight to ninety-six hours.

Because of this risk, public health guidance has been that people should avoid foraging wild mushrooms and should only eat commercially purchased mushrooms. Caregivers are urged to watch young children where mushrooms grow, and pet owners should keep animals away from wild fungi. Anyone who ate wild mushrooms and develops vomiting, diarrhea, or abdominal pain should seek immediate medical evaluation; clinicians are advised to contact the California Poison Control System for case management and possible transfer to a liver transplant center.

The outbreak has hit communities that speak Spanish, Mixteco, and Chinese, and several patients required intensive care; a few have received liver transplants. The state hotline, 1-800-222-1222, is available for the public and providers who need advice.