Death Cap Mushroom (Amanita phalloides): Features, Symptoms, and What to Do

The death cap (Amanita phalloides) is one of the most dangerous mushrooms in the world. It contains amatoxins, the group of toxins behind more than 90% of mushroom-related deaths worldwide. These toxins are not destroyed by cooking, drying, or freezing, and the first symptoms of poisoning are delayed by many hours. That delay is what makes it so dangerous: by the time someone feels ill, the toxin has usually already reached the liver. If you think anyone, including a pet, may have eaten a wild mushroom that could be a death cap, treat it as an emergency now, not when symptoms start. In the United States, call Poison Control on 1-800-222-1222; in Australia, call the Poisons Information Centre on 13 11 26; elsewhere, contact your local poison service or emergency number.

This guide explains what the death cap is, the features specialists use to describe it, why those features are not a safe basis for eating anything, what poisoning looks like, and why this European fungus is now a growing concern in places such as California, British Columbia, and Australia.

Key facts at a glance

Question	Short answer
Scientific name	Amanita phalloides, family Amanitaceae
Main toxins	Amatoxins (amanitins)
Does cooking make it safe?	No. Amanitins are heat stable; boiling, drying, and freezing do not help
When do symptoms start?	Usually 6 to 24 hours after eating, which is later than most food poisoning
Main organs harmed	Liver and kidneys
Where it grows	Under oaks and some other broadleaf trees; native to Europe and introduced elsewhere

Why the death cap is so dangerous

Three things combine to make this mushroom unusually deadly.

A very small dose is enough

The CDC’s report on a 2016 California outbreak notes that a lethal dose of amatoxin can be as low as 0.1 mg per kilogram of body weight, while a single mushroom can contain up to 15 mg. The State Herbarium of South Australia puts it in plainer terms: one third of a cap can kill a child.

The toxin survives the kitchen

Many people assume that thorough cooking neutralises anything harmful in a mushroom. It does not work here. The amanitins are heat stable, and California’s public health department warns that cooking, boiling, drying, or freezing death caps does not make them safe. Taste is no guide either: the same warning notes that death caps can look and taste similar to safe mushrooms.

It attacks the cell’s protein-making machinery

At the cellular level, amanitins bind to and block RNA polymerase II, the enzyme cells need to read their genes and make new proteins. A 2021 review in the journal Toxins explains that the liver is hit hardest because liver cells take up amanitins efficiently through specific transporters, and part of the toxin is recycled between the bile and the gut, prolonging exposure. Most of the absorbed toxin leaves through the urine, which is one reason the kidneys can also be damaged.

How specialists describe the death cap

The descriptions below come from herbarium and museum references. They are here so you can understand warnings and recognise when a mushroom needs to be left alone. They are not a checklist for deciding that a mushroom is safe to eat. Individual specimens vary, features change with age and weather, and other dangerous Amanita species share many of the same traits.

Feature	What references describe	Why it is easy to miss
Cap	Usually 3 to 12 cm across; greenish, olive, yellowish or olive-brown, often paler at the edge	Colour fades, and some caps are almost white
Gills	White to cream, crowded, and free from the stem	Young buttons have no visible gills at all
Ring	A white, skirt-like ring on the upper stem	It can collapse, stick to the stem, or wash off
Base	A swollen bulb wrapped in a white, sac-like cup called a volva	The cup is often buried and stays behind if the stem is snapped off
Spore print	White	Several look-alikes also have pale prints
Smell	Sweetish when young, becoming unpleasant with age	Smell is subjective and never a safety test

The University of British Columbia’s Beaty Biodiversity Museum stresses that the cup at the base is often underground and easy to miss. This is one of the most important lessons in mushroom safety: a mushroom picked by snapping the stem can lose the very feature that would have raised the alarm.

Habitat and season

The death cap is mycorrhizal, which means it lives in partnership with the roots of living trees rather than feeding on dead wood. In its native Europe it is strongly associated with oaks, and it is also recorded under hornbeam, sweet chestnut, and other broadleaf trees. In cities it can appear in lawns, parks, and gardens wherever suitable host trees are planted. The UBC museum notes that it has turned up on irrigated lawns in mid-summer, so a garden mushroom is not automatically a harmless one.

Fruiting is closely tied to moisture. Large flushes tend to follow wet weather, which is why outbreaks of poisoning often come after heavy rains. Our explainer on how rain and weather trigger wild mushroom flushes covers the general pattern, and why fall is peak mushroom season explains why autumn brings so many species above ground at once.

The look-alike problem

Many death cap poisonings do not involve people knowingly eating an unknown mushroom. They happen when someone is confident they have found something familiar. Published case reports and herbarium guides describe several recurring mix-ups.

Mistaken for	Why the mix-up happens	What specialists point out
Paddy straw mushroom (Volvariella volvacea)	Both have a cup at the base, and people who know straw mushrooms from Asian markets may look for this feature	Straw mushrooms have no ring and have pink gills and spores; wild straw mushrooms are rare or absent in many regions where death caps are common
Puffballs	Young death cap “eggs” are round and white before the cap opens	Slicing a death cap egg from top to bottom reveals the outline of a developing mushroom inside
Other Amanita species	Many amanitas share a ring, white gills, and a volva	Several are also deadly, and separating them can require expert examination
Stubble rosegill and smooth white parasol	Pale caps, white or pale stems, similar size	The South Australian herbarium lists the stubble rosegill as a look-alike that has been confused with the death cap with fatal results

The UBC museum records three cases in British Columbia that show how ordinary these mistakes can be. In 2003 a man in Victoria ate young death caps from his front yard, believing they were puffballs. In 2008 a woman in Langley ate death caps she thought were straw mushrooms. Both survived after extended hospital stays. In 2016 a three-year-old child in Victoria died after eating death caps growing on a downtown property.

This is why we repeat the same message in every foraging article on this site. A photo, a diagram, an app, or a written description cannot confirm that a wild mushroom is safe to eat. If you are interested in wild mushrooms, our comparison of wild versus cultivated mushrooms explains why buying from reputable sources removes this risk, and our guide to true and false morels shows how similar problems arise with other species.

What death cap poisoning looks like

Amatoxin poisoning follows a recognisable pattern. The CDC report summarises it as delayed gastroenteritis, a period of apparent recovery, and then liver and multi-organ failure.

1. The silent period (about 6 to 24 hours). The person usually feels fine. Toxin is already being absorbed.
2. The gastrointestinal phase. Severe, watery diarrhoea, vomiting, and abdominal cramps begin suddenly. Dehydration can be serious. In the 2016 California outbreak, symptoms typically began 7 to 12 hours after eating.
3. The false recovery (around 24 to 36 hours). Gut symptoms ease and the person may seem to be getting better, while liver damage continues. California’s 2025 warning specifically calls this improvement misleading.
4. Organ failure (typically 3 to 5 days). Signs of liver failure appear, sometimes with kidney failure, bleeding problems, and confusion.

Because the early symptoms look like a stomach bug, the illness can be misdiagnosed. In the 2016 California outbreak, one patient was first sent home with a diagnosis of gastroenteritis and returned the next day. Telling doctors that wild mushrooms were eaten, and when, matters enormously.

What the 2016 and 2025 California outbreaks show

The CDC investigation describes 14 suspected death cap poisonings in northern California over about two weeks in December 2016, after the Bay Area Mycological Society warned of an unusually large flush. Three patients needed liver transplants, including a child left with permanent neurological impairment. Some of the mushrooms had been picked by acquaintances and shared, and one group of young men believed they had found hallucinogenic mushrooms.

The pattern repeated in late 2025. On 5 December 2025, the California Department of Public Health reported 21 cases identified by the California Poison Control System, mainly in the Monterey and San Francisco Bay areas, including one adult death, and urged people not to gather wild mushrooms that season.

What to do if someone may have eaten one

Act on the possibility, not on symptoms. Waiting for illness wastes the hours when care is most useful.

• Call your poison control service or emergency number immediately, even if the person feels well.
• Go to hospital if advised, and do not wait for vomiting or diarrhoea to begin.
• Keep any leftover mushrooms, uncooked pieces, or peelings and take them with you so a specialist can examine them.
• Write down what was eaten, how much, when, and who else shared the meal. Everyone who ate it needs assessment.
• Do not try home remedies or induce vomiting unless a medical professional tells you to.
• If a dog may have eaten a wild mushroom, contact a vet or an animal poison service immediately. The UBC museum notes that death caps are also poisonous to pets, especially dogs.

What treatment involves

Hospital care centres on aggressive fluid and electrolyte replacement, close monitoring of liver and kidney function, and drugs intended to limit how much toxin reaches liver cells. In the 2016 outbreak, all patients received intravenous fluids, octreotide, and silibinin, a compound derived from milk thistle. Severe cases may need a liver transplant.

It is important to be honest about the evidence. The 2021 Toxins review states that there is no international consensus on how to manage death cap poisoning and that no randomised controlled trials have tested these treatments. Most clinical evidence comes from retrospective case series. This is why prevention, and early contact with poison specialists, matter so much. Milk thistle products sold as supplements are not a substitute for hospital treatment.

An invasive mushroom on the move

The death cap is native to Europe, but it now grows on several other continents. Genetic work led by Anne Pringle, published in Molecular Ecology in 2009, found strong evidence that California’s death caps came from Europe, probably carried on the roots of imported trees. The earliest confirmed Californian collections date from 1938, and the study estimated that the fungus has been spreading at an average of roughly 5 km per year. Crucially, it appears to have partnered with the native coast live oak, allowing it to move from planted trees into native woodland.

The species is now recorded from southern California to British Columbia, and herbarium records in Australia list it from several states and territories. Because it fruits near homes, schools, and parks under planted trees, people who have never thought of themselves as foragers can encounter it. Families with young children and dogs in areas where it occurs should know what it looks like and remove mushrooms from play areas, wearing gloves or washing hands afterwards.

Common myths that put people at risk

• “Poisonous mushrooms taste bad.” California health officials warn that death caps can taste similar to safe mushrooms. Taste is no warning.
• “Cooking destroys mushroom toxins.” Not amatoxins.
• “It looks like a mushroom I already know.” A species that is easy to recognise in a market or in another region can have a deadly look-alike where you live, as the straw mushroom cases show.
• “I only ate a little.” A small amount can still be dangerous. Seek help regardless of how much was eaten.

The takeaway

The death cap does not need to make you afraid of mushrooms, but it should change how you think about wild ones. Enjoy cultivated mushrooms from shops and growers, or grow your own from known spawn; our beginner’s guide to mushroom growing is a good starting point. If you want to learn about wild fungi, join a local mycological society, learn from experts in person, and treat identification as a lifelong skill rather than something an app or article can provide. And if there is any chance someone has eaten a death cap, call for help immediately.

Sources and further reading

• CDC MMWR: Amanita phalloides Mushroom Poisonings, Northern California, December 2016 (2017)
• California Department of Public Health: death cap warning, news release NR25-023 (5 December 2025)
• Le Daré, Ferron and Gicquel: Toxic Effects of Amanitins, Toxins 13(6):417 (2021)
• Pringle et al.: Amanita phalloides was introduced and is expanding its range on the west coast of North America, Molecular Ecology 18:817–833 (2009)
• State Herbarium of South Australia: Death Cap fact sheet
• UBC Beaty Biodiversity Museum: Amanita phalloides, death cap

This article is for general education and is not medical advice. It cannot be used to identify mushrooms for eating.