The California Public Health Department is warning residents to completely avoid foraging for wild mushrooms, as highly toxic "death cap mushrooms," nicknamed "death caps," are thriving across the state and are easily mistaken for edible varieties.

Since 18/11/2025, the department has recorded over 30 cases of death cap mushroom poisoning, resulting in four fatalities and three liver transplants. Many hospitalized individuals have suffered acute liver damage, which progressed rapidly to liver failure. Cases have spanned a wide age range, from 19 months old to 67 years old.

Craig Smollin, medical director of the San Francisco Division at the California Poison Control System, described the dozens of death cap mushroom poisoning cases reported this year as "very unusual," noting that typically only two to three cases are recorded annually.

Experts attribute this year's massive proliferation of death cap mushrooms in California to warm, early rainy weather.

Death cap mushrooms blooming in California. *AP*

The death cap mushroom is among the world's most toxic species, belonging to a small group of mushrooms containing amatoxin, a potent compound responsible for approximately 90% of mushroom poisoning fatalities globally. This species can be found in both urban parks and forests, often growing under oak trees, and closely resembles many edible mushroom varieties. Its appearance also changes through different growth stages, from a white cap to a greenish cap. "It is very hard to identify without deep mushroom research expertise," Dr. Smollin stated.

Consuming even a small amount of the mushroom can be fatal. Experts warn that the mushroom's color is not a reliable indicator of its toxicity. Furthermore, drying or cooking does not diminish the death cap mushroom's toxins. Those poisoned typically experience abdominal pain, nausea, and diarrhea within the initial 24 hours. While these early symptoms may subside within a day, severe liver damage, which can lead to death, continues to develop silently over two to three days.

In Salinas, northern California, Laura Marcelino's family mistakenly picked death cap mushrooms, believing they were similar to types she and her husband had foraged in their native Mexico. Both parents suffered from vomiting and had to miss work. Marcelino was hospitalized for five days, while her husband required a liver transplant. Fortunately, their young children did not consume the mushrooms as they disliked them.

Health officials noted that many of this year's poisoning victims speak Spanish, Mixtec, and Mandarin, prompting them to broaden warnings in multiple languages. Sixty percent of the poisoning cases in this outbreak involved Spanish speakers.

Duc Trung (AP, US News, USA Today)