About Poisonous Mushrooms

Contents

More on Specific Fungal Toxins

 

Eating Wild Mushrooms

Edible wild mushrooms can be delicious, interesting and nutritious additions to the diet. Mushroom hunting can also be a fun and healthy outdoor activity that allows a person to get in touch with wild landscapes around them.

But some mushrooms can make you sick or kill you!

Only eat wild mushrooms that have been identified. Only eat mushrooms that are well known and popular as edibles. Experimenting can be dangerous. Stick with a couple, or half a dozen species and learn them well.

There are no simple or general rules for telling poisonous mushrooms from edible ones:

  • Poisonous mushrooms do not turn silver black

  • Poisonous mushrooms don’t turn rice, onions or garlic a particular colour

  • Poisonous mushrooms are all different; no particular colour, texture, odour or taste is a sure sign that mushrooms are either safe or dangerous

  • Poisonous mushrooms grow in many habitats, a mushroom on wood is not always poisonous and mushrooms in meadows are not all edible

  • Poisonous mushrooms might be eaten by animals and some animals are not affected by mushroom poisons. Animals may eat things and die later

  • Mushrooms that peel easily are not necessarily edible

 

General Safety Considerations

Mushrooms can spoil and cause food poisoning like any food. Old, partially deteriorated and poorly stored mushrooms cause problems.

Mushrooms should only be gathered from pristine habitats. Pesticides and agricultural chemicals, petroleum products and heavy metals may be found in mushrooms growing near roadways or in urban, agricultural or industrial areas. Pet wastes can contaminate mushrooms in parks and along trails.

Mushrooms should always be thoroughly cooked; raw and undercooked mushrooms often cause problems. Some mushrooms such as true morels contain small amounts of toxins when fresh but are safe after cooking.

Eat mushrooms in moderation; eating a large amount of any food can cause problems.

Eating even a good edible mushroom again and again may eventually result in development of an allergic sensitivity. Mushrooms are not easily digested by humans, especially if undercooked, partly because we have no enzymes to digest chitins.

 

Major Types of Mushroom Poisoning:

There are several recognized types or classes of mushroom poisonings, mostly identified by the toxins the mushrooms contain.

As a rule, the longer it takes for illness to occur after eating toxic mushrooms, the more serious the poisoning. Deadly mushrooms often take 6 to 36 hours, or even several days or weeks, before the first symptoms appear. By this time toxins are completely absorbed and treatment is very difficult. Severe damage occurs to organs such as the liver and kidneys, and death is possible.

When sickness begins just a few minutes or within a couple hours after eating mushrooms, the outlook is usually fairly positive, though often still very unpleasant for the sufferer. Many mushrooms cause rapid-onset gastrointestinal irritation that resolves within a short time. Vomiting and diarrhea often expel unabsorbed toxins, and after replacement of lost fluids and with rest, recovery is usually complete.

It is always important to try and identify what type of mushroom has caused a poisoning but there is a saying in mushroom toxicology: “Treat the patient, not the mushroom”.

Show Table: Mushroom Toxin, Onset, and Symptoms

Toxin group: Mushrooms involved

Time of onset

Symptoms

Deadly Cyclopeptides

Amanita species in subgenus Lepidella, Conocybe in subgenus Pholiotina, some Galerina and Lepiota species

6 to 12 hours (up to 36 hours)

Colicky abdominal pain, vomiting, watery diarrhea: symptoms subside after about one day; then about 72 hours post ingestion, gastrointestinal symptoms recur along with signs of impending liver failure.

Orellanine

Cortinarius species in subgenus Leprocybe

36 hours to 21 days

Nausea, vomiting, abdominal pain; night sweats, rigors, chills, headache; reduced urination, excessive urination, kidney failure.

Gyromitrin

Gyromitra species; Helvella, Morchella and Verpa species are suspect.

5 to 12 hours

Bloating, nausea, vomiting, diarrhea, abdominal pain; headache, dizziness, fatigue, fever; jaundice; rarely haemolysis.

Coprine

Coprinus atramentarius, some other Coprinus species suspect.

5 to 10 minutes after drinking alcohol: mushrooms eaten in preceding 3 to 5 days

Flushing of face and neck, metallic taste, tingling or numbness of hands and feet, fast pulse, chest pain, hypotension, nausea and vomiting may occur.

Muscarine

Clitocybe and Inocybe species, and Mycena pura.

15 minutes to 2 hours

Perspiration, salivation, lacrimation; blurred vision, narrowing of pupils; slow pulse, hypotension; abdominal cramps, diarrhea, excessive salivation,  wheezing, breathlessness.

Ibotenic acid/muscimol

Amanita muscaria, Amanita pantherinoides and Amanita gemmata

15 minutes to 2 hours

Drowsiness, confusion, dizziness, uncoordinated movements, delirium, illusions, muscle twitching, deep sleep.

Psilocybin/psilocin

Some Psilocybe species, also Conocybe, Gymnopilus and Panaeolus species

10 to 30 minutes

Euphoria, drowsiness, mood changes, laughter, anxiety, hallucinations, uncoordinated movements, muscle weakness, dysphoria with fear or panic.

Gastrointestinal irritants

Gomphus, Gymnopus (Collybia), Hebeloma, Hypholoma, Lactarius, Laetiporus, Leucoagaricus, Russula, Tricholoma and Tylopilus species. Diverse species, esp. if under-cooked

15 minutes to several hours, usually less than 4 hours.

Nausea, vomiting, abdominal cramps, diarrhea.

Kidney failure

Amanita smithiana

4 to 11 hours

Nausea, vomiting, possible diarrhea, abdominal pain; possible muscle pain;  reduced urination, excessive urination, kidney failure.

Immune haemolytic anemia

Paxillus involutus

Within two hours. Accumulative, after repeated ingestions.

Vomiting, diarrhea, abdominal pain, collapse with hypotension; anaemia, haemolysis, haemoglobinuria, kidney pain and kidney failure. Acute gastrointestinal irritation is also caused by this mushroom.

Specific Mushroom Toxin Details

 

Deadly Cyclopeptides: Also known as Amanitin or Deadly Amanita poisons

The Death Cap has recently been found growing with urban imported trees in the Greater Vancouver area and Vancouver Island, and is expected to spread. The Destroying Angels, Amanita virosa and Amanita verna, are not known to occur in British Columbia. These mushrooms and close relatives are responsible for most mushroom deaths around the world.

Several little brown mushrooms or “LBM”s grow in British Columbia that contain the same deadly poisons as Death Caps. Galerina species and Conocybe filaris are found where magic mushrooms grow, and could be picked and eaten by mistake.

First symptoms usually occur between 8 to 12 hours after these mushrooms are eaten, though onset may be as short as 6 hours or as long as 36 hours. First there is sudden cramping abdominal pain, vomiting and watery diarrhea, sometimes with flecks of blood and mucus visible. Intense diarrhea often results in severe dehydration. After about 24 hours these severe symptoms often cease and the patient appears to be in remission.

About 72 hours after ingestion a second wave of vomiting, diarrhea and cramping begins and liver damage becomes apparent with jaundice and swelling of the liver, the swollen area being tender to the touch. Liver destruction is usually rapid and often ends in death. The last stages often involve gastrointestinal bleeding, delirium, convulsions and coma. The entire course from first symptoms to death takes about 7 to 10 days. Liver transplantation may be attempted to prevent death.

 

Orellanine: Deadly Cortinarius Delayed Kidney Failure

Certain medium sized orange to reddish-brown Cortinarius mushrooms cause delayed kidney failure. The first symptoms often do not appear until 3 days or even much longer after eating the mushrooms. In some cases first symptoms have appeared after 21 days!

Symptoms are typically nausea, vomiting, abdominal pain, night sweats, headache, chills and shivering, frequent urination and thirst, lack of energy and appetite, generalized muscle and joint pain, and possible irreversible kidney failure.

Several species of Cortinarius that may contain these toxins are found in British Columbia. It is even possible that poisonings have occurred without being detected as having been caused by mushrooms. Can you remember everything you ate three weeks ago?

 

Allenic Norleucine (aminohexadienoic acid) and Chlorocrotylglycine

Amanita smithiana is a frequent cause of very serious poisoning causing kidney failure when mistaken for the edible and prized Pine Mushroom Tricholoma magnivelare. Deaths have not yet been reported, but poisoning will result in extended hospitalization, typically for a month or longer, and treatment involves repeated hemodialysis sessions until kidney function resumes.

Symptoms appear 4 to 11 hours after eating this mushroom and are nausea, vomiting, possible diarrhea, abdominal pain; possible myalgia; delayed polyuria, oliguria, kidney failure.

 

Gyromitrin: Monomethylhydrazine

Mushrooms known as False Morels and Elves’ Saddles, species of Gyromitra and Helvella, can contain large amounts of Gyromitrin, which breaks down into the toxin Monomethylhydrazine or MMH. MMH has both short-term or acute, and long-term consequences when consumed. MMH is also volatile, which means that it evaporates or boils off, producing toxic fumes when these mushrooms are cooked.

The first symptoms in acute Gyromitra poisoning usually appear 6 to 12 hours after eating. Occasionally symptoms may come on as soon as 2 hours or as late as 24 hours after the meal.  First there may be a sudden sensation of bloating with nausea and vomiting, and often diarrhea which may be watery with some blood present. Lethargy, dizziness and exhaustion occur with general abdominal pain and severe headache. There may also be fever.

After 36 to 48 hours in severe cases, liver, kidney and nervous system damage may be evident. Jaundice, fever, delirium, convulsions and coma may result. Rarely breakdown of the blood, and liver and kidney failure may occur.

Monomethylhydrazine and related compounds are known to be carcinogens, causing liver cancer. Many edible mushrooms, including the cultivated button mushroom, contain small amounts. This is one reason why all edible mushrooms should be cooked, and why mushrooms should always be consumed in moderation.

 

Coprine: Mushroom and Alcohol interaction

The Inky-cap mushroom, Coprinus atramentarius, and relatives contain compounds that cause illness following the consumption of alcohol. These substances interrupt the metabolism of alcohol, resulting in accumulation of toxic acetaldehyde in the blood. If these mushrooms were eaten any time from 30 minutes to 3 days before alcohol is consumed, symptoms occur within 5 to 10 minutes after drinking. This syndrome can also occur if the mushrooms are eaten when alcohol is already present in the body. Symptoms include flushing and reddening of the face, neck and chest, swelling of the face and hands, feeling of warmth, numbness and tingling of the arms and legs, metallic taste in the mouth, heart palpitations, severe headache, sweating, anxiety, vertigo and dizziness, confusion, weakness, nausea and vomiting.

This toxin is similar in action to Antabuse or disulfiram, a drug once used for aversion therapy for severe alcoholism. Some other mushrooms are known to interact with alcohol and produce similar illness, but the mechanism is not known.

 

Muscarine: Drool, Sweat and Tears

Many mushrooms in different groups contain this toxin, especially species of Inocybe and Clitocybe. Some Inocybe and Clitocybe mushrooms are very common in British Columbia and grow in both natural and urban environments. Symptoms usually develop in 15 minutes to 30 minutes after eating the mushrooms. The symptoms most characteristic of this type of poisoning are profuse sweating, salivation and tear production. It is rarely fatal.

Other symptoms include nausea, vomiting and abdominal cramps with diarrhea, slow heart beat and slow pulse, blurred vision with constricted pupils, wheezing and difficulty in breathing, and a painful urge to urinate. This type of poisoning is rarely fatal.

 

Ibotenic Acid / Muscimol: Inebriating “Magic Mushrooms”

The Fly Agaric, Amanita muscaria, is the classic red-capped toadstool with whitish warts familiar from illustrations in fairy tales and children’s books. Colourful images of the Fly Agaric are used to decorate everything from Christmas tree ornaments to cookie jars. It also has the reputation of being deadly poisonous, which it is not. The Fly Agaric and its close relative, Amanita gemmata, and the Western Panther Cap, Amanita pantherinoides produce inebriation and sometimes delirium.

The effects begin 15 minutes to 2 hours after eating the mushrooms, and symptoms last 4 to 12 hours or sometimes as long as 24 hours. Alcohol-like inebriation results in lack of coordination and difficulty in moving, standing and walking. Lethargy may alternate with excitation and manic behavior. Dizziness, confusion, delirium, agitation and drowsiness may progress to a deep coma-like sleep lasting several hours. Nausea and vomiting may occur. In children and small pets especially, muscle twitching, jerking, cramping and spasms or even generalized seizures may occur.

The amounts of ibotenic acid and muscimol present in Amanita muscaria, Amanita pantherinoides and Amanita gemmata mushrooms are extremely variable, as are individual reactions to these toxins. As a result they are extremely unpredictable recreational intoxicants. The intoxication may be even further complicated if the person is on medication, or under the influence of other drugs including alcohol or caffeine. The possibility of accidental physical injury during this sort of intoxicated state is also always of concern.

Several colour varieties of Amanita muscaria exist and vary in toxin content. In British Columbia there are at least four varieties; Amanita muscaria variety flavivolvata with bright red cap and yellowish veil remnants, which is predominant in western coastal North America, variety formosa with orange to yellow caps, variety alba which has whitish to cream coloured caps and the rare brown capped variety regalis.

The reputation of Amanita muscaria as a deadly mushroom is highly exaggerated. Around the world and through history, deaths from these mushrooms are very rare. In one fatal case on Vancouver Island, a young person suffocated on vomit while unconscious after eating Amanita pantherinoides to get high.

 

Psilocybin / Psilocin: Hallucinogenic “Magic Mushrooms”

Mushrooms such as Liberty Caps, Psilocybe semilanceata, which contain psilocybin and psilocin, take effect 10 to 30 minutes after being consumed, and these effects last for 4 to 5 hours, or somewhat longer if large amounts have been eaten. About one gram of dried mushrooms is a common recreational dose. The intensity and length of effects depend on the amount consumed.

The first sign of activity is a brief period of yawning, rapidly followed by a sense of exhilaration, euphoria with a tendency toward being introspective and meditative, inability to concentrate, uncontrollable laughter, confusion, visual hallucinations involving colours and shapes and also the senses of sound and touch, and distortion of time and space perception. Pupils are dilated. There is often muscle weakness and difficulty in walking. Rapid heartbeat and increased blood pressure can occur, especially in cases of a panic reaction. Depending on set and setting a person may experience either a great positive feeling of euphoria, or an equally great sense of dysphoria resulting in a bad trip with feelings of profound uneasiness leading to fear or panic.

Young children react differently than adults to magic mushrooms, and may develop high fevers and convulsions. In at least one case this may have caused death.

 

Gastrointestinal Irritants

A wide variety of mushrooms cause gastrointestinal upset. Most poisonous mushrooms as well as most mushroom poisonings fall into this category.

Onset of symptoms may be 5 minutes to 4 hours after eating mushrooms. Nausea, vomiting, abdominal pain and diarrhea are the most common symptoms. Fluid loss may be of concern. There may also be headache, chills, sweating, salivation, weakness, disorientation, hallucination and dizziness. Prickling, tingling and itching of the skin or extremities may be experienced, and anxiety and panic may cause hyperventilation.

Toxins are varied and many species have not been studied. Various mechanisms may be involved, including a direct gastrointestinal irritation, a central nervous system-mediated emetic effect, disruption of intestinal flora by antibiotic substances, food intolerance, possible pesticide contamination, and bacterial contamination from decomposing mushrooms.

Not all species will cause gastrointestinal effects in all people. Some reactions may be due to allergy, or food intolerance which may be seen with digestive enzyme deficiencies (alpha-trehalase deficiency). Consumption of large amounts of reportedly edible mushrooms can also cause indigestion, especially if the mushrooms are not fully cooked.

In February 2009 a report claimed that Amanita franchetii had caused ten deaths in Jiangxi Province, China. Symptoms reported were nausea, vomiting, diarrhea, general aching, abdominal distension and pain and dizziness. Death occurred about a week after mushrooms were eaten. Amanita franchetii is very common in Haida Gwaii and should be considered a dangerous mushroom.

 

Anomalous Edible Mushroom Poisonings & Symptoms

Even commonly eaten mushrooms may cause reactions, due to individual differences in the human consumer — i.e. allergies, sensitivities, or pre-existing medical conditions, individual differences in the particular mushroom — i.e. habitat or genetic variance, or improper preparation. See below for notable cases of mushroom poisonings from “edible” mushrooms.

Show Table: Anomalous Edible Mushroom Poisonings, Onset, and Symptoms

Mushroom involved

Time of onset and notes

Symptoms

Laetiporus sulphureus and Laetiporus conifericola

Gastrointestinal upset.

Neurotoxic in one case

Gastrointestinal 5 to 45 minutes. Often results from under-cooked or over-mature mushroom

Neurotoxic about one hour after eating raw, in child.

Causes nausea, vomiting, dizziness, abdominal pain, headache and fatigue, tingling of extremities.

Also disorientation, ataxia, hallucinations.

Morchella species

Gastrointestinal upset

5 to 45 minutes. Toxic when eaten raw, alcohol consumed may also cause problems.

Nausea, vomiting and abdominal pain and cramping.

Pleurocybella porrigens

Encephalopathy: Deaths reported in Japan

2 to 3 weeks. Patients all had kidney disease, most had received dialysis prior to ingestion.

Tremor, weakness of extremities, disturbance of consciousness, intractable seizures; cerebral cortex lesions.

Tricholoma equestre or Tricholoma flavovirens

Rhabdomyolysis: Deaths reported in France

1 to 4 days following repeated meals (3 or more) over two weeks or more.

Fatigue, muscle weakness and pain, anorexia, nausea, profuse sweating, myogloburia; kidney failure.

Lentinula edodes

Flagellate Erythema

24 hours to 5 days after eating raw or lightly cooked fresh shiitake mushrooms

Red itchy linear rash (like lash-marks) usually on the trunk but also arms, legs, neck and head.