Mushrooms can be a delicious and nutritious addition to many dishes. However, some types of mushrooms are poisonous and can cause severe illness or even death if ingested. It’s important to be able to identify poisonous varieties and avoid them.
Of the thousands of mushroom species, only about 100 are known to be poisonous. While most poisonous mushrooms contain toxins that cause gastrointestinal distress, a few contain deadly toxins that can destroy the liver or kidneys, or cause neurological damage. The deadliest of all is the death cap mushroom.
The Death Cap Mushroom
The death cap mushroom, known scientifically as Amanita phalloides, is by far the most poisonous mushroom in the world. This highly toxic fungus is found throughout many parts of Europe, North Africa, Asia, and the Americas. It has been associated with the majority of deadly mushroom poisonings worldwide.
Death cap mushrooms resemble edible straw mushrooms and caesar’s mushrooms, which makes them even more hazardous. They have olive-green to greenish-yellow caps (4-12 cm diameter), white gills, white stalks, and a sack-like structure (volva) at the base of the stalk. Their scientific name derives from their unfortunate resemblance to the edible Amanita caesaria mushroom.
Toxins in the Death Cap Mushroom
The death cap mushroom contains two groups of toxins – amatoxins and phallotoxins. Amatoxins are cyclic peptides that inhibit RNA polymerase II, an enzyme needed for DNA transcription and protein synthesis. This causes impaired liver, kidney and central nervous system function, eventually leading to organ failure and death. The amatoxins found in the death cap mushroom are:
Phallotoxins bind to and stabilize filamentous actin, causing damage to the kidney tubules. The combination of amatoxins and phallotoxins make the death cap mushroom particularly deadly.
Amount of Toxins
The concentration of toxins varies between mushrooms, seasons, and geographic locations. On average, the amatoxin content ranges from about 0.1 to 0.6 mg per g of mushroom, while the phallotoxin content is an order of magnitude lower.
As little as 0.1 mg per kg of body weight of amatoxins is considered a potentially fatal dose. This means that ingesting just half a death cap mushroom could kill an adult human. The cyclopeptide toxins can withstand heat and freezing, so they retain potency even when mushrooms are cooked.
Symptoms of Poisoning
Death cap poisonings cause a wide range of symptoms. After ingestion, there is typically:
- A period with no symptoms (6-24 hours)
- Sudden onset of gastrointestinal distress (vomiting, diarrhea, cramps)
- A temporary recovery period (up to 2 days)
- Liver and kidney failure leading to jaundice, seizures, coma
- Potentially death from organ failure (6-16 days after ingestion)
Diagnosis is based on symptoms together with a history of mushroom ingestion. However, the death cap mushroom can sometimes be misdiagnosed as a viral gastroenteritis since the initial symptoms mimic stomach flu.
Treatment for Death Cap Poisoning
There is no antidote for death cap mushroom poisoning. Treatment consists of aggressive fluid therapy and other supportive measures. The following interventions may improve survival if implemented early on:
- Gastric decontamination to prevent further toxin absorption
- IV fluids to maintain electrolyte balance
- Activated charcoal to reduce toxin absorption
- Silymarin or N-acetylcysteine to protect the liver
- Dialysis to remove toxins
- Liver transplant if liver failure occurs
With proper supportive care, the survival rate is about 50-80%. However, survivors may suffer long-term impairment of liver or kidney function.
Fatal Dose and Toxicity
Here is a comparison of the fatal dose and toxicity levels of death cap mushrooms versus other poisons:
|Death cap mushroom
|0.1 mg/kg amatoxins
|0.1 mg/kg body weight
|Puffer fish tetrodotoxin
*LD50 is the dose required to kill 50% of test animals like mice or rats
As shown above, the amatoxins in the death cap mushroom are extremely toxic compared to other lethal poisons. Just a small amount can be fatal.
Here is a map showing countries and regions where the death cap mushroom can be found:
In Europe, the death cap is especially prevalent in southern Germany, Switzerland, Slovenia, and Poland. In North America, it is found along the U.S. Pacific coast from California to British Columbia, and parts of the U.S. Northeast. It has also been reported from parts of South America and South Africa.
In the past, most poisonings were concentrated in Europe. However, the geographic range of the death cap mushroom continues to expand with accidental introductions into new areas. For example, death cap poisonings in California increased after an infestation was identified in the 1930s.
Since death cap mushrooms often grow in suburban areas and near deciduous trees, it’s crucial to be able to properly identify them. Here are some key identification tips:
- White gills that do not turn brown
- Presence of a volva or cup at the base
- Green-yellow cap color (not white)
- No ring around the stem
- Bulbous base of the stem
Always err on the side of caution – if you aren’t 100% sure, don’t eat it!
Avoiding Death Cap Poisoning
Here are some ways you can avoid potentially fatal poisonings from death cap mushrooms:
- Learn how to identify local mushrooms accurately
- Only collect mushrooms with trusted experts
- Never eat foraged mushrooms raw
- Cook unknown mushrooms thoroughly (does not destroy toxins)
- Avoid alcohol consumption with meals containing foraged mushrooms
- Only eat a small amount of wild mushrooms at first
- Avoid mushrooms growing in suburban yards or near deciduous trees
When in doubt, remember that there is no way to differentiate edible from poisonous species just by sight. Consuming even a piece of a death cap mushroom can be deadly.
First Aid for Mushroom Poisoning
If someone is showing signs of mushroom poisoning, quickly take the following first aid steps:
- Call emergency medical services
- Take the victim and a sample of the suspect mushroom to the hospital
- Rinse mouth and give water to dilute remaining toxins
- Induce vomiting if advised by poison control
- Activated charcoal may help absorb toxins
Early and aggressive treatment is critical for survival in death cap mushroom poisoning cases.
The death cap mushroom is responsible for the vast majority of mushroom poisonings worldwide, due to its severe toxicity and close resemblance to edible species. Just half a mushroom contains enough deadly amatoxins to kill an adult. There is no antidote, so prompt medical care is essential.
Anyone who forages for mushrooms should be familiar with the identification features and habitat of the death cap mushroom. Consuming even a small piece can be fatal without urgent medical treatment. When unsure, remember that there is absolutely no room for error when wild mushroom foraging.