Fungi Poisoning: Mushroom Toxin Types, Signs, Treatment

Most are not, but the ones that are can kill. Wikipedia's article on mushroom poisoning puts the number of toxic species at about 100 out of roughly 100,000 known fungal species, and notes that in one analysis 21.2% of North American species examined were poisonous against 12.1% of European ones.

A 2014 review in the journal Mycobiology (Jo, Hossain and Park) gives a wider frame: about 140,000 mushroom species estimated worldwide, 14,000 identified, and about 700 with documented pharmacological activity. The authors name poor knowledge and misidentification as the leading causes of poisoning.

"Fungi poisoning" is not only about mushrooms. Wikipedia lists ergotamine from Claviceps, the ergot fungus that grows on rye, as a cause of poisoning through contaminated grain rather than a mushroom someone picked.

Doctors group mushroom poisoning by the toxin, because the toxin decides how soon symptoms start and which organ is at risk. The Mycobiology review classifies seven main syndromes; the Merck Manual sorts them into early and delayed. Combined:

• Amatoxins (death cap, destroying angels, Galerina, Lepiota). 6 to 12 hours with no symptoms, then about a day of gut symptoms, then liver damage 1 to 3 days after eating (Wikipedia). Hospitals use activated charcoal, silibinin, N-acetylcysteine, high-dose penicillin G and, in liver failure, transplantation (Mycobiology review; Wikipedia).
• Orellanine (webcaps, Cortinarius). Kidney failure 3 to 20 days after eating (Wikipedia; Merck gives the same window). Treated with haemodialysis (Mycobiology review).
• Gyromitrin (false morels). 8 to 12 hours; vomiting, diarrhoea, dizziness and tremor, then possible liver damage and destruction of red blood cells; the review names pyridoxine (vitamin B6) as the main antidote, and notes exposure can also come from breathing cooking vapour.
• Muscarine (Inocybe, some Clitocybe, Omphalotus). About 30 minutes; sweating, tears, saliva, small pupils, slow heart. Treated with atropine; most people recover within 24 hours (Merck Manual).
• Ibotenic acid and muscimol (fly agaric, panther cap). 30 minutes to 2 hours; confusion, hallucinations, drowsiness (Wikipedia).
• Psilocybin (Psilocybe, Panaeolus). Effects from 20 to 90 minutes; in children coma, fever and seizures have been reported (Merck Manual; Mycobiology review).
• Coprine (common ink cap). Only with alcohol: flushing, nausea and palpitations 5 to 10 minutes after a drink (Wikipedia).
• Gut irritants (green-spored parasol and many lawn mushrooms). 1 to 6 hours; vomiting and diarrhoea, usually over within 24 hours (Merck Manual).
• Muscle breakdown (some Tricholoma and Russula) and nerve damage (some Clitocybe, Pleurocybella porrigens, Hapalopilus rutilans) are rarer delayed syndromes that the Merck Manual says can be fatal.

None of these treatments is something to try at home. They are listed so you know why the hospital needs to know what was eaten and when.

Vomiting and abdominal pain: the Merck Manual says every poisonous mushroom causes them. What matters is when they start.

• Within about 2 hours: usually one of the less dangerous groups, such as gut irritants, psilocybin or muscarine (Merck Manual).
• 6 hours or more after eating: the dangerous group. Death cap poisoning starts with vomiting and diarrhoea 6 to 12 hours after the meal, and about half of people with this type of poisoning die within 5 to 8 days, according to the Merck Manual's consumer edition.

The deadliest mushrooms give no sign for hours, so the eating itself is the signal to call Poison Control, not the first symptom. Our page on food poisoning from mushrooms lists onset times species by species.

Getting to hospital early, with the mushroom. There is no single antidote; treatment depends on the toxin, which is why doctors ask for a sample.

Speed changes the outcome for the deadliest group. Wikipedia reports that for amatoxin poisoning, mortality was about 10% in patients hospitalised soon after eating and 50 to 90% in those admitted 60 hours or more later. Reviews of treated cases put overall amatoxin mortality at around 10 to 15% by 1995, down from 22.4% in a 1971 to 1980 European series (Wikipedia, Amanita phalloides).

For the green-spored parasol, the most commonly eaten poisonous mushroom in North America, University of Florida IFAS Extension says there is no antidote and hospital care is fluids and anti-nausea medicine.

What you can do right now:

• Call Poison Control at 1-800-222-1222 (US) or your local emergency number, even if the person feels fine.
• Keep what is left. Any uneaten mushroom, or others from the same spot, in a paper bag or waxed paper rather than plastic, refrigerated (North American Mycological Association advice for pet cases, which applies equally to people).
• Photograph it from above, below and the whole stem with its base.
• Write down the time it was eaten and when any symptoms began.
• Do not try home remedies or wait to see what happens.

The death cap, Amanita phalloides. Wikipedia estimates that 30 grams, about half a cap, can kill an adult and attributes about 90% of mushroom deaths to it; the Merck Manual gives 95%. Its toxins are heat-stable, so cooking, freezing or drying does not help.

The same amatoxins occur in destroying angels, in Galerina (the funeral bell) and in some small Lepiota species (Mycobiology review), which is why a small brown lawn mushroom can be as dangerous as the large white Amanitas. See death cap, destroying angel, funeral bell and deadly Lepiota.

Wikipedia lists mistaken identity as the cause of most cases, and gives the typical swaps:

• Death cap taken for the paddy straw mushroom (Volvariella volvacea), a familiar edible in Asia.
• Young Amanitas in their egg stage taken for puffballs or for the shaggy mane.
• Jack-o'-lantern taken for chanterelles.
• Funeral bell (Galerina) taken for psilocybin mushrooms by people collecting them to get high.
• Children eating lawn mushrooms, where the green-spored parasol is a common culprit.

Folk tests do not help. Wikipedia lists as false: bright colours mean poison, animals avoid toxic mushrooms, poison blackens silver, toxic mushrooms taste bad, cooking makes any mushroom safe, and poisonous mushrooms turn rice red. The Merck Manual adds that even knowledgeable people find it hard to tell poisonous from harmless mushrooms. See toxic look-alikes.

If someone has eaten a wild mushroom, a clear photo of the cap, gills and whole stem base helps the poison centre and any mushroom expert they call in narrow down the toxin group. MushroomLens can suggest what a mushroom might be from the same photos. No app, photo or website can tell you a wild mushroom is safe to eat; after an ingestion, call first and identify second.

Research and drafting for this page were assisted by AI and checked line by line against the sources listed below. Nothing on this page says a wild mushroom is safe to eat or safe to handle. If you find an error, tell us and we will correct it.