Mushroom poisoning can be life-threatening. If someone has eaten a poisonous mushroom (or plant), don’t try to treat them yourself – seek medical help immediately.
If someone has accidentally consumed poisonous mushroom, please see this information at the end of the blog post.
Disclaimer. I do not have a medical background so this blog post is purely for information and should not be relied on to decide if you require treatment or not.
This is written from a UK perspective and ignores poisonous species not found in the UK. It does not give detailed identification information.
When I tell people that I pick and eat wild mushrooms, the usual reaction is to tell me that I'm brave. This fear of mushrooms, “mycophobia” is prevalent among British, the main concern being some mushrooms are poisonous if eaten. Mushroom poisoning means harmful consequences from consuming toxic substances present in some. Let’s put some perspective on this:
- Globally, of 100,000 known fungi species about 100 are thought to be poisonous to humans.
- In the UK, we have about 4500 species. Of these, about 200 are edible, 50 poisonous and the rest are inedible or tasteless.
- Most mushroom poisonings are not fatal.
- Fatalities are extremely rare, the most recent deaths from mushroom poisoning in Britain were in 2012 and 2008.
- You will not be ill from touching a poisonous species. Don’t put your fingers in your mouth, nose, eyes etc and wash them before eating anything.
There are mainly five explanations as to why people get mushroom poisoning:
- Misidentification – confusing a toxic mushroom with an edible species. Usually this is due to mistakenly eating a “look-a-like” with a similar appearance or a lack of knowledge
- Consuming certain species while uncooked or undercooked.
- Young children accidentally ingesting mushrooms while crawling on a lawn.
- Individuals attempting suicide or homicide.
- Individuals looking for a hallucinatory high.
In this post we concentrate on the first two reasons and help foragers avoid mushroom poisoning. We don’t want to put you off. By limiting yourself to species you can identify with confidence, eating picking and wild mushrooms is safer than walking down the road. Mushroom hunting is one of the greatest pleasures the countryside offers. The fact that many are poisonous, in my view, adds to, rather than detracts from the fun!
Avoiding Mushroom Poisoning
- NEVER eat any fungus if you are not absolutely sure of its name and you know that it is safe to eat.
- Familiarise yourself with the poisonous species such as the Death Cap and the Yellow Stainer.
- Avoid picking young specimens, that have not developed fully, as they are more difficult to identify.
- Stick to a selection of easy to recognise species that you feel confident about. Be aware of any possible “look-a-likes”.
- Learn from a good field guide or, better still, by going out with an expert. We run day long fungus forays and 3 hour fungus walks with our focus on teaching identification skills. See also our blog post on Identifying Mushrooms.
We recommend you avoid:
- Small brown mushrooms (except Autumn Chanterelles (Craterellus tubaeformis)).
- Any mushroom with red on it.
- All Amanitas - mushrooms with white gills, a swollen base or bag at the base of the stem and, usually, a large ring on the stem.
- Any mushroom with brown spores.
- Young mushrooms that are still at the “egg” stage. They are very difficult to identify. If eating Puffballs, cut them in half lengthwise. Young Puffballs in the edible stage have undifferentiated white flesh within; whereas the gills of immature Amanita mushrooms can be seen if they are closely examined.
In a bit more detail:
- Unfamiliar Species: Check and re-check your identification, especially looking out for a similar poisonous species. If still in doubt, ask an expert or throw it away.
- Examine each specimen. Always check each specimen in case a different species has got in amongst your collection of edible ones.
- Keep your collections separate. Do not mix edible and non-edible species in your basket if you are collecting for the pot. It is a good idea if collecting for the pot to only collect edible species and not other species for identification purposes - the spores of some species can be deadly.
- Check the spore print. A simple operation, leaving a cap on some paper and covering for an hour or so. This will help check your identification.
- Do not eat raw wild fungi. Some wild fungi are poisonous if eaten raw, e.g. Morels (Morchella species) Wood Blewit (Clitocybe nuda), the Blusher, (Amanita rubescens) or species of Helvella. Always cook your collections. Heat destroys the toxins in these species, in the same way that it does for Kidney beans.
- Retain an uncooked specimen. This is a very sensible idea. Keep one example of what you have eaten in the fridge. In case, you do poison yourself, this will help others identify what you have eaten and therefore know how to treat you. Different species contain different toxins; therefore, treatments will vary.
- Only eat good specimens. Many poisoning cases occur when edible species are eaten in poor condition – decaying / dirt. Only eat good specimens - microscopic fungi and bacterial infection can occur in decaying mushrooms. Food poisoning can be caused by collecting old or partly rotten specimens, collecting in plastic bags or closed containers, or through spoilage by incorrect long-term storage.
- Keep your collections in the fridge. This keeps your specimens in good condition.
- Experimenting. If experimenting and eating a type for the first time, only eat a small amount. Different people react to fungi in different ways and it is safer to test your own body out gently! A classic cause of gastric upset is Chicken of The Woods (Laetiporus sulphureus). Roughly 9/10 people get on with it, but about 1 in 10 is ill from it.
- Alcohol. Avoid drinking alcohol with species you haven't eaten before and with certain species, e.g. the Common Ink Cap (Coprinus atramentarius)
- Fear. Do not feed wild mushrooms to people who don't want to eat them. Fear can make people sick.
- Susceptible people. Do not serve wild fungi to young children, old or sick people. Their resistance to mushroom toxins may be lower.
- Greed. Do not eat large quantities of wild mushrooms in one sitting. This alone can make you sick.
Source: How to avoid mushroom poisoning (adapted from Shelley Evans' guidelines in Guides for the Amateur Mycologist - No.4 Guide for the Kitchen Collector: Preservation and Cooking of Fungi. British Mycological Society, 1994)
Types of Mushroom Poisoning
Each poisonous mushroom species contains one or more toxins, which may be classified based on the mushroom’s physiologic and clinical effects in humans, the target organ toxicity, and the time to symptom onset. The clinical spectrum and toxicity vary with the following factors:
- Species consumed
- Amount consumed
- Preparation method
- Individual response to the toxins
A. Rapid Onset Mushroom Poisoning
With this category, symptoms appear within 6 hours of eating a mushroom. These are usually are not life-threatening; they may last a few hours, occasionally a few days. There are five basic types of rapid-onset mushroom poisonings.
Species involved: Various
The most common type of rapid onset mushroom poisoning is usually gastrointestinal upset - vomiting and diarrhoea. Typically, there is no long-term damage. It is recommended that medical assistance should still be sought if this type of poisoning is suspected particularly in the case of children.
2. Alcohol Sensitisation
Species involved: Common Ink Cap (Coprinus atramentarius)
These mushrooms contain the toxin coprine, which causes an Antabuse-like reaction. Antabuse is a drug given to alcoholics to make them sick if they drink alcohol. Symptoms begin within minutes of ingesting alcohol (including medications) up to 5 days after eating the mushroom.
3. PSL (perspiration/salivation/lacrimation) syndrome
- St George’s Mushroom (Calocybe gambosa)
- Agaricus species (Field Mushroom (A. campestris) / Horse Mushroom (A. arvensis) etc)
The toxic substance is muscarine. Symptoms may include sweating, dizziness, muscle twitching, confusion, coma and occasionally seizures. With treatment nearly all people recover in 24 hours. Without treatment, death can occur in a few hours with severe poisoning. One fatality was recorded in Surrey in 1937.
Symptoms are delusions, euphoria or anxiety, altered space and time, and occasionally seizures, especially in children. These symptoms go away without treatment, and serious consequences are rare, so specific treatment is usually not needed.
They may be eaten intentionally or accidentally by humans and pets and should be suspected whenever the victim is described as "acting drunk”. The toxins are ibotenic acid/muscimol. Symptoms may include apparent intoxication, in-coordination, hyperactivity, muscle spasms, collapse, anxiety, visions, and finally, a coma-like sleep. Fly Agaric has been used ritually for thousands of years as an inebriant.
B. Delayed Onset Mushroom Poisoning
These are life-threatening, late-onset poisonings, where symptoms appear over 6 hours after ingestion. The results are organ failure potentially resulting in death. Serious symptoms do not always occur immediately after eating, often not until the toxin attacks the kidney or liver, sometimes days or weeks later. The types are based on the symptoms resulting from the toxin in the mushrooms consumed.
1. Gastrointestinal/headache/liver damage
Species involved: False Morel (Gyromitra esculenta)
Mistaken Species: False Morels have been confused with the highly prized mushrooms Morels (Morchella species).
The toxin involved is monomethylhydrazine (MMH). Symptoms are delayed vomiting, diarrhoea and a low blood sugar level. Other problems include brain toxicity (such as seizures) and, after a few days, liver and kidney failure. While not 100% confirmed, a lady died and 18 people were taken ill following eating a dish containing Morels in a restaurant in Valencia, Spain. Initial blame pointed to the Morels.
2. Gastrointestinal/liver damage
The toxins involved are amatoxins. The first two species listed below are both members of the Amanita genus. While there are some edible members of this genus, our advice for beginners is to avoid them all. Another point is that young specimens of Amanitas at an immature or “egg” stage look completely different and are easy to confuse with other species. With the stem not developed and no cap yet, the mushroom is still entirely encased in their universal veil and you won’t be able to identify them with any confidence.
Death Cap (Amanita phalloides)
The Death Cap is the most dangerous and poisonous mushroom, responsible for 90–95% of fatal mushroom poisonings globally. Just one mushroom is likely to contain enough toxins to kill an average adult human. The toxins are not destroyed by cooking, boiling, soaking, or drying. It is widely distributed in Europe and has spread to Australia, Asia, Southern Africa, and the Americas on the roots of imported trees. I see it in the UK about 3 or 4 times each year. It is reported as being palatable (tasty).
There is no complete antidote for Death Cap mushroom poisoning – survival depends on early diagnosis and treatment. Vomiting and diarrhoea start in 6 to 12 hours. Sometimes the blood sugar level drops dangerously low. Symptoms subside for a few days, but then people develop liver failure and sometimes kidney failure. Liver failure causes the skin to turn yellow (jaundice). People with kidney failure may have reduced urination or may have stopped urinating. Sometimes the symptoms disappear on their own, but about half of the people who have this type of poisoning die in 5 to 8 days. People with liver failure may survive if given a liver transplant. IN 2018, a lady in Essex was hospitalised after eating Death Caps. She survived.
Death Caps have been mistaken for other species, especially when immature, even by people with some experience in identifying mushrooms. A proportion of the fatalities from consuming Death Caps are cases where people have been used to picking and eating edible Amanita in their home country and have then moved to a different country and picked and consumed Death Caps by mistake. These include the Thai lady that died on the Isle of Wight from eating Death Caps. Also, unfortunately, in 2 weeks in September 2015, there were over 40 cases of mushroom poisoning in Germany, where refugees from other countries confused Death Caps with edible Amanita species.
- Shaggy Ink Caps / Lawyers Wigs (Coprinus comatus)
- Puffballs – with young Amanitas at the “egg” stage
- Field Mushrooms (Agaricus campestris)
- Green Cracking Russula (Russula virescens)
- Asian Paddy-Straw Mushrooms (Volvariella volvacea) – not found in the UK.
- Edible Amanitas including The Blusher (Amanita rubescens) and Tawny Grisette (Amanita fulva)
Destroying Angel (Amanita virosa)
This is another member of the Amanita genus which contains the same toxins as the Death Cap.
Read here someone's experience of nearly dying after eating Destroying Angels.
The Dapperlings (Lepiota species)
- Young Parasol Mushrooms (Macrolepiota procera) and Shaggy Parasols (Macrolepiota rhacodes)
- Fairy Ring Champignon (Marasmius oreades)
3. Kidney, later liver damage.
- Wood Blewitt (Clitocybe nuda)
- Chanterelles (Cantharellus cibarius)
- Ceps (Boletus edulis)
- Autumn (winter) Chanterelles (Craterellus tubaeformis)
The toxin involved is orellanine. Vomiting and diarrhoea may last for 3 days. Kidney failure, with symptoms of flank pain and a decreased amount of urine, may occur 3 to 20 days after the mushrooms are eaten. Kidney failure often resolves spontaneously.
In the UK, there are cases of these being accidentally consumed leading to kidney failure including holiday makers in Scotland in 1972 as well as Nicholas Evans, author of The Horse Whisperer, his wife and two other relatives. Evans had assumed they were Ceps but overlooked that the mushrooms had gills rather than pores. All four victims were informed that they would require kidney transplants in the future. Several years later, Evans received a kidney donated by his daughter. The other three eventually received transplants after some searching for donors, despite Charlotte having only eaten three mouthfuls of mushroom.
What to do in the case of accidentally consuming a poisonous mushroom
Adapted from NHS poisoning treatment information. Numbers / links are for UK residents.
Being poisoned can be life-threatening. If someone has eaten a poisonous mushroom (or plant), don’t try to treat them yourself – seek medical help immediately.
If they’re showing signs of being seriously ill, dial 999 to request an ambulance or take them to your local A&E department.
Symptoms associated with serious poisoning include:
- being sick
- sudden, noticeable heartbeats (palpitations)
- breathing difficulties
- uncontrollable restlessness or agitation
- seizures (fits)
- drowsiness or loss of consciousness
Call NHS 111 for advice if a person who’s been poisoned doesn’t appear to be seriously ill.
Helping someone who’s conscious
If you think someone has been severely poisoned and they’re still conscious, ask them to sit still and stay with them while you wait for medical help to arrive.
If they’ve been poisoned by eating a mushroom, try to get them to spit out anything that is remaining in their mouth.
Helping someone who is unconscious
If you think someone has eaten a poisonous mushroom and they appear to be unconscious, try to wake them and encourage them to spit out anything left in their mouth. Don’t put your hand into their mouth and don’t try to make them sick.
While you’re waiting for medical help to arrive, lie the person on their side with a cushion behind their back and their upper leg pulled slightly forward, so they don’t fall on their face or roll backwards. This is known as the recovery position.
Wipe any vomit away from their mouth and keep their head pointing down, to allow any vomit to escape without them breathing it in or swallowing it. Don’t give them anything to eat or drink.
If the person isn’t breathing or their heart has stopped, begin CPR (cardiopulmonary resuscitation) if you know how to.
How to help medical staff
Medical staff will need to take a detailed history to effectively treat a person who’s been poisoned. When the paramedics arrive or when you arrive at A&E, give them as much information as you can, including:
- What mushroom you think the person may have eaten.
- When the mushroom was eaten (how long ago)?
- If it was cooked.
- How much was eaten (if you know)?
- Any alcohol consumed?
- Had the patient consumed this mushroom before?
- Is a specimen of the mushroom available?
- Is a photograph of the mushroom available?
- How long after ingestion did symptoms begin?
- Details of any symptoms the person has had, such as whether they’ve been sick.
Take a sample of the mushroom and photographs with you for accurate identification. If there is any of the food left over take a sample of that too.
Medical staff may also want to know:
- the person’s age and estimated weight
- whether they have any existing medical conditions
- whether they’re taking any medication (if you know)
There is an excellent Facebook group Poisons Help; Emergency Identification For Mushrooms & Plants. If you can post pictures of the mushroom (or plant) and give your geographic location (e.g. Dorset / UK) you will get a rapid identification from extremely knowledgeable people around the globe.