Amanita Species Mushroom Poisonings - Northern California, November 2025-March 2026

The genus Amanita contains approximately 600 species of mushrooms, including some that produce amatoxins, which can lead to liver failure and death when ingested. Poisonous mushrooms often resemble and are difficult to distinguish visually from nonpoisonous, edible mushrooms. After above-average late November 2025 rainfall in California, regional mycologists observed numerous Amanita mushroom blooms in regional parks and area wildlands. On November 18, 2025, specialists at the San Francisco division of the California Poison Control System (CPCS) suspected amatoxin-containing mushroom poisoning in two patients who gastrointestinal symptoms and hepatotoxicity after eating foraged wild mushrooms. Over the next 17 weeks (November 18, 2025-March 17, 2026), 39 cases of suspected amatoxin mushroom poisoning in patients who had eaten foraged wild mushrooms were reported to CPCS. These 39 cases were characterized by a pattern of delayed onset of gastrointestinal symptoms and hepatotoxicity; 32 (82%) patients recovered, three (8%) required liver transplants, and four (10%) died. CPCS and the California Department of Public Health Toxicological Outbreak Program coordinated a response that included a statewide health advisory and educational materials translated into multiple languages for the public; collectively, the affected patients spoke at least six languages other than English. This is the largest reported outbreak of mushroom-associated hepatotoxic poisoning in California history and the largest in the United States in several decades. This was also the first outbreak of this size in which some persons ate Amanita ocreata, another poisonous Amanita species. The morbidity and potential lethality associated with amatoxin-containing mushroom ingestion is a serious public health concern. Educational materials, including for non-English-speaking communities, during the late fall to mid-spring when fruiting of amatoxin-containing mushrooms occurs, might reduce the number of poisonings.