A surge in deadly mushroom poisoning cases in California has resulted in four deaths and at least three people requiring liver transplants, health authorities have confirmed. The incidents are linked to the consumption of death cap mushrooms, which have proliferated across the state following an unusually rainy winter.

The California Department of Public Health has urged residents to completely avoid mushroom foraging, warning that death cap mushrooms closely resemble edible varieties and are extremely difficult to identify safely.

Rising cases alarm health officials

Since November 18, 2025, more than three dozen cases of death cap mushroom poisoning have been reported in California. Health officials said several patients developed rapidly progressing acute liver injury and liver failure. While three patients required liver transplants, four deaths have also been recorded. Those affected ranged in age from just 19 months to 67 years.

Some patients required intensive care treatment, highlighting the severity of exposure even in small quantities.

What makes death cap mushrooms deadly

Death cap mushrooms are considered among the most poisonous in the world. They contain amatoxins, potent toxins responsible for nearly 90 per cent of fatal mushroom poisonings globally. These mushrooms are commonly found in city parks, forests and especially under oak trees.

Dr Craig Smollin, medical director of the California Poison Control System in San Francisco, said such a high number of cases in a single season is highly unusual. Experts noted that neither cooking nor drying reduces the toxin’s potency.

A family’s close call

Speaking to the San Francisco Chronicle, Laura Marcelino from Salinas said her family mistook death cap mushrooms for familiar edible varieties. While she recovered after hospitalisation, her husband required a liver transplant.

The Associated Press reported that US Poison Centers have seen a 40 per cent rise in mushroom exposure cases this season.

Symptoms to watch for

Common symptoms include nausea, vomiting, diarrhoea and abdominal cramps. Experts warn that early symptoms may subside within a day, but severe liver damage can develop within two to three days.