San Mateo County, California – After an individual in San Mateo County got very sick after eating death cap mushrooms, health officials are advising people to stay away from wild mushrooms. The warning comes after recent rain made the circumstances perfect for these very poisonous mushrooms to proliferate throughout California.
County health authorities say that death cap mushrooms are now common in some areas of Northern California and along the Central Coast. These mushrooms have amatoxins in them, which are very strong poisons that can kill you if they get into your liver.
Officials say the mushrooms often grow near oak and pine trees and can closely resemble edible varieties, making them especially dangerous even for experienced foragers. If pets eat the mushrooms while outside, they are also at risk.
County Health Officer Dr. Kismet Baldwin-Santana emphasized that no preparation method can make death cap mushrooms safe to eat.
“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.”
State health data suggest that the number of severe poisoning cases has gone up significantly. From November 18, 2025, to January 6, 2026, health officials in Northern California and the Central Coast, from Sonoma County to San Luis Obispo County, reported 35 cases of amatoxin poisoning. Three adults died and three more needed liver transplants during that time. On the other hand, there are usually less than five of these incidents documented in a normal year.
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Symptoms of death cap mushroom poisoning usually start six to twenty-four hours after eating them. They can include nausea, vomiting, watery diarrhea, stomach pain, and dehydration. In some situations, symptoms seem to go better for a short time before serious liver failure sets in one to four days later. This pattern can make it harder to get the help you need.
Health experts strongly warn people to only eat mushrooms that they buy from well-known grocery stores or commercial sources. If you think you might have eaten a wild mushroom or are showing signs of poisoning, you should get medical help right away. You can call California Poison Control at 1-800-222-1222 any time of day or night for expert help and advice.
