Mushroom Poisoning: Symptoms, Timing and What to Do

Every autumn, as wild mushrooms pop up in lawns, parks and woods, poison centres take calls from worried parents, foragers and pet owners. Most mushroom exposures turn out to be mild. But a small number of species can cause liver failure, kidney failure or death, and the early signs can be misleadingly gentle.

This guide explains the main types of mushroom poisoning, why the timing of symptoms matters so much, who is most at risk and exactly what to do if someone eats a wild mushroom. It’s based on guidance from the Merck Manual, the US Centers for Disease Control and Prevention (CDC), the Oregon Poison Center, NSW Health in Australia and other expert sources.

If someone has eaten a wild mushroom, don’t wait for symptoms. Call your poison centre now. In the US, Poison Control is 1-800-222-1222. In Australia, the Poisons Information Centre is 13 11 26. If the person is struggling to breathe, collapses or has a seizure, call your emergency number.

This article is general information and can’t replace medical advice.

How common is mushroom poisoning?

A CDC report published in 2021 estimated that in 2016 there were around 1,328 emergency department visits and 100 hospital stays in the United States after people accidentally ate poisonous mushrooms. Looking at insurance records for 2016 to 2018, the researchers found that 8.6% of patients had a serious outcome. The most common were:

Serious outcome	Share of patients (CDC, 2016 to 2018)
Abnormal heart rhythm	2.7%
Acute kidney failure	2.2%
Liver failure	1.8%
Muscle breakdown (rhabdomyolysis)	1.4%
Seizure	1.4%

The authors note that many poisonings probably go unreported, so the true numbers may be higher. Deaths weren’t included in their analysis, because data on deaths weren’t available to them.

The key rule: timing matters

The Merck Manual, a medical reference written for health professionals, groups mushroom poisonings by how quickly symptoms start. It says mushrooms that cause symptoms early are “less dangerous than those that cause symptoms later.” Early onset generally means within about 2 hours of eating, and late onset usually means after 5 hours.

That’s counter-intuitive. People often assume that if they feel fine an hour after a meal, the mushrooms were safe. With some of the deadliest species, the opposite can be true.

NSW Health says people may get sick anywhere from 30 minutes to 24 hours after eating a mushroom, depending on the type, the amount eaten and their general health. Some syndromes described by the Merck Manual start even later.

Early-onset poisoning

Type	Example mushrooms (Merck Manual)	Typical onset	Main symptoms
Stomach upset (gastroenteritis)	Chlorophyllum molybdites and small brown lawn mushrooms	Early	Vomiting and diarrhoea, sometimes headache or muscle aches. Usually settles within 24 hours
Muscarinic	Some Inocybe and Clitocybe species	Within 30 minutes	Sweating, watering eyes and mouth, small pupils, slow heart rate. Usually settles within 12 hours
Hallucinogenic	Mushrooms containing psilocybin	15 to 30 minutes	Hallucinations, fast heart rate and raised blood pressure
Isoxazole	Fly agaric and panther cap (INCHEM)	30 to 90 minutes	Drowsiness, confusion, agitation, muscle twitching

Early-onset poisonings can still be serious, especially in children, older people or anyone with health problems. Our article on the fly agaric covers one of these in detail.

Delayed-onset poisoning: the dangerous group

Type	Example mushrooms (Merck Manual)	Typical onset	What happens
Amatoxin poisoning	Death cap (Amanita phalloides) and related Amanitas	Stomach symptoms 6 to 12 hours after eating	Followed by liver failure and sometimes kidney failure
Gyromitra poisoning	False morels (Gyromitra)	Delayed	Low blood sugar, nervous system effects such as seizures, then possible liver and kidney damage
Cortinarius poisoning	Some Cortinarius species	Stomach upset lasting about 3 days	Kidney failure 3 to 20 days after eating
Muscle damage	Some Tricholoma species	24 to 72 hours	Breakdown of muscle (rhabdomyolysis)

The Merck Manual says the death cap is “the most toxic” Amanita and is responsible for 95% of deaths from mushroom poisoning. Our guide to the death cap explains how to recognise it, and our article on true and false morels covers the Gyromitra risk.

Rarer delayed syndromes

The Merck Manual also lists some less familiar delayed poisonings, which show how varied mushroom toxins can be:

• Amanita smithiana: can cause delayed stomach upset and acute kidney failure, usually 1 to 2 weeks after eating.
• Some Clitocybe species: can cause painful, burning, red hands and feet (erythromelalgia) about 24 hours after eating.
• Angel wings (Pleurocybella porrigens): linked to altered consciousness, convulsions and death, with onset anywhere from 1 to 31 days after eating.
• Some Russula species: can affect the heart muscle, causing abnormal rhythms.

These syndromes are uncommon, but they’re a reminder that “I felt fine the next day” is no guarantee that a wild mushroom was safe.

Why waiting is risky

With the death cap, the Merck Manual describes stomach symptoms starting 6 to 12 hours after the meal, followed by liver failure. With some Cortinarius species, kidney failure can follow days or even weeks later. By the time the most serious damage shows, hours or days have passed. This is why medical advice is to call for help straight away after eating an unknown wild mushroom, rather than waiting to see what happens.

Who is most at risk?

The CDC report and other sources highlight several groups:

• Young children. NSW Health says young children are at higher risk “because they often put things in their mouths.” The CDC notes that small children may take exploratory bites while playing outside. Serious outcomes in young children were less common than in older patients in the CDC data, but they do happen.
• Foragers. The CDC report says “amateur mushroom foragers might not distinguish poisonous from nonpoisonous species.” It found that most poisonings appeared to come from foraging for food rather than from people seeking hallucinogenic effects.
• People new to an area. The CDC notes that recent immigrants may mistake toxic local species for edible mushrooms they know from home.
• Older or unwell people. The Oregon Poison Center warns that “children, older adults, and people who are already ill may be sickened by mushrooms that are edible by others.”

Myths that put people at risk

Myth	The reality
“Cooking makes it safe.”	The CDC and NSW Health both say cooking doesn’t remove mushroom toxins. NSW Health adds that soaking, peeling or drying don’t either
“There’s a simple test for poisonous mushrooms.”	The Merck Manual calls folklore identification tests “unreliable”
“If it’s edible for me, it’s edible for everyone.”	The Oregon Poison Center says “No edible mushroom is tolerated by 100% of all people”
“A field guide or online forum is enough.”	The Oregon Poison Center advises: “Do not only rely on local field guides or online forums for identification”
“An app can tell me if it’s safe.”	Studies of identification apps found frequent errors. See our article on mushroom identification apps

What to do if someone eats a wild mushroom

1. Act now, don’t wait. NSW Health advises calling the poison centre without waiting for symptoms.
2. Call the right number. Use your emergency number if the person has trouble breathing, has swelling around the mouth or face, or loses consciousness, as the Oregon Poison Center advises. Otherwise call your poison centre (US 1-800-222-1222, Australia 13 11 26).
3. Collect evidence. NSW Health suggests taking a photo or sample of the mushroom to help identify it. The Merck Manual notes that an uneaten specimen can be sent to a mycologist for expert identification.
4. Note the details. Write down what was eaten, how much, when, and when any symptoms started. Timing helps doctors work out which type of poisoning is likely.
5. Check others who ate it. If several people shared the meal, everyone should be assessed, even if they feel fine.
6. Don’t try home remedies. Don’t make the person vomit unless a poison centre or doctor tells you to. INCHEM, for example, advises against it for fly agaric poisoning.

How it’s treated

The Merck Manual says that treatment for most mushroom poisonings is “symptomatic and supportive”. This means treating dehydration, low blood sugar, seizures or other problems as they arise. Doctors may give activated charcoal to reduce absorption. For the most serious cases, such as liver failure after amatoxin poisoning, specialist hospital care is needed, and the Merck Manual says a liver transplant may be required.

How to prevent mushroom poisoning

• Only eat wild mushrooms identified by an expert. This is the CDC’s first recommendation.
• Supervise young children outdoors where mushrooms grow, and clear mushrooms from lawns and play areas.
• Buy from reliable sources. Shop-bought and cultivated mushrooms are the safe choice for most people. Our guide to wild vs cultivated mushrooms explains why.
• Learn with experts. If you want to forage, join a local mushroom club or guided foray and learn your local dangerous species first.

The bottom line

Most mushroom exposures are mild, but a few species can be deadly, and the most dangerous ones often cause symptoms late. If anyone eats a wild mushroom they can’t be completely sure of, call a poison centre straight away, keep a sample, and don’t wait to see if symptoms appear.

Sources and further reading

• O’Malley, G. F. and O’Malley, R. (reviewed 2025). Mushroom Poisoning. Merck Manual Professional Edition
• Gold, J. A. W., Kiernan, E., Yeh, M., Jackson, B. R. and Benedict, K. (2021). Health Care Utilization and Outcomes Associated with Accidental Poisonous Mushroom Ingestions, United States, 2016 to 2018. MMWR 70(10): 337 to 341
• Oregon Poison Center, OHSU (2024). Mushroom Safety
• NSW Health (updated 2026). Wild mushroom poisoning
• Piqueras, J. (1990, reviewed 2000). Amanita muscaria, Amanita pantherina and others. IPCS INCHEM Poisons Information Monograph G026
• Wisconsin Mycological Society: If You Suspect a Poisoning

Featured image: death cap by Chuck Wilson via iNaturalist (CC0 1.0).