Foraging for wild mushrooms may seem like a harmless hobby, but California health officials say it can turn deadly.

The California Department of Public Health (CDPH) has confirmed 21 cases of toxic mushroom poisoning in recent weeks, likely caused by the highly dangerous death cap mushroom. One adult has died, and several others have required intensive care.

“An outbreak of serious illness associated with eating foraged wild mushrooms has been reported,” CDPH said in a statement. “We are urging individuals to avoid foraging for and eating wild mushrooms while the risk of amatoxin poisoning is high.”

The cases were reported between mid-November and Dec. 5. While many incidents were clustered in Monterey County and the San Francisco Bay Area, state officials warn the danger exists across California. The California Poison Control System is now monitoring the situation.

Monterey County officials also issued a warning after local hospitals reported a spike in poisonings.

“Only people with extensive training and experience should eat wild mushrooms that they have picked themselves,” said Monterey County Health Officer Dr. Edward Moreno, noting that toxic and non-toxic mushrooms can look nearly identical.

Death Caps Linked to Severe Liver Damage

Health officials believe the outbreak is connected to Amanita phalloides, commonly known as the death cap mushroom. According to CDPH, several patients have suffered severe liver damage, including one case that may require a liver transplant.

“Death cap mushrooms contain potentially deadly toxins that can lead to liver failure,” said CDPH Director and State Public Health Officer Dr. Erica Pan. “Cooking, boiling, drying, or freezing does not make them safe.”

The Bay Area Mycological Society calls death caps “strikingly beautiful,” but also the number one cause of fatal mushroom poisonings worldwide. The species originated in Europe and first appeared in California in 1938. It is now found throughout the state and across the globe.

Scientists estimate death caps cause 10,000 illnesses and 100 deaths worldwide each year, according to NPR.

Other Dangerous Mushrooms

Other poisonous species commonly found in California include:

• Amanita ocreata – known as the Death Angel

• Amanita muscaria – known as the Fly Amanita

Because of the risk, CDPH advises the public not to forage for wild mushrooms at all during this season.

Symptoms Can Fade — Then Turn Fatal

Rainfall in fall and winter creates ideal conditions for toxic mushrooms to grow, especially near oak and hardwood trees, CDPH said.

Symptoms of poisoning often begin six to 24 hours after eating wild mushrooms and may include:

• Watery diarrhea

• Nausea and vomiting

• Abdominal pain

• Dehydration

While these symptoms may disappear within a day, severe liver failure can develop 48 to 96 hours later, even if the person feels better.

Anyone who becomes sick after eating wild mushrooms should seek medical attention immediately. Health care providers are urged to contact the California Poison Control System at 1-800-222-1222 for treatment guidance.

The warning comes just months after Arizona health officials cautioned residents not to lick toxic toads following seasonal rains — another reminder that nature can carry serious risks when ignored.