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Types of Mushroom toxins

The different types of toxins that are known to occur in mushrooms. These types of toxins are: Amanitoxins, Gyromitrin, Orellanine, Muscarine, Ibotenic Acid, Muscimol, Psilocybin, Coprine.

Mushroom poisonings are generally categorized by their physiological effects. There are four categories of mushroom toxins:

  • Protoplasmic poisons (poisons that result in generalized destruction of cells, followed by organ failure)

    Amatoxins: Several mushroom species, including the Death Cap or Destroying Angel (Amanita phalloides, A. virosa), the Fool's Mushroom (A. verna) and several of their relatives, along with the Autumn Skullcap (Galerina autumnalis) and some of its relatives, produce a family of cyclic octapeptides called amanitins. Poisoning by the amanitins is characterized by a long latent period (range 6-48 hours, average 6-15 hours) during which the patient shows no symptoms. Symptoms appear at the end of the latent period in the form of sudden, severe seizures of abdominal pain, persistent vomiting and watery diarrhea, extreme thirst, and lack of urine production. If this early phase is survived, the patient may appear to recover for a short time, but this period will generally be followed by a rapid and severe loss of strength, prostration, and pain-caused restlessness. Death in 50-90% of the cases from progressive and irreversible liver, kidney, cardiac, and skeletal muscle damage may follow within 48 hours (large dose), but the disease more typically lasts 6 to 8 days in adults and 4 to 6 days in children. Two or three days after the onset of the later phase, jaundice, cyanosis, and coldness of the skin occur. Death usually follows a period of coma and occasionally convulsions. If recovery occurs, it generally requires at least a month and is accompanied by enlargement of the liver. Autopsy will usually reveal fatty degeneration and necrosis of the liver and kidney.

    Hydrazines: Certain species of False Morel (Gyromitra esculenta and G. gigas) contain the protoplasmic poison gyromitrin, a volatile hydrazine derivative. Poisoning by this toxin superficially resembles Amanita poisoning but is less severe. There is generally a latent period of 6 - 10 hours after ingestion during which no symptoms are evident, followed by sudden onset of abdominal discomfort (a feeling of fullness), severe headache, vomiting, and sometimes diarrhea. The toxin affects primarily the liver, but there are additional disturbances to blood cells and the central nervous system. The mortality rate is relatively low (2-4%). Poisonings with symptoms almost identical to those produced by Gyromitra have also been reported after ingestion of the Early False Morel (Verpa bohemica). The toxin is presumed to be related to gyromitrin but has not yet been identified.

    Orellanine: The final type of protoplasmic poisoning is caused by the Sorrel Webcap mushroom (Cortinarius orellanus) and some of its relatives. This mushroom produces orellanine, which causes a type of poisoning characterized by an extremely long asymptomatic latent period of 3 to 14 days. An intense, burning thirst (polydipsia) and excessive urination (polyuria) are the first symptoms. This may be followed by nausea, headache, muscular pains, chills, spasms, and loss of consciousness. In severe cases, severe renal tubular necrosis and kidney failure may result in death (15%) several weeks after the poisoning. Fatty degeneration of the liver and severe inflammatory changes in the intestine accompany the renal damage, and recovery in less severe cases may require several months.

  • Neurotoxins (compounds that cause neurological symptoms such as profuse sweating, coma, convulsions, hallucinations, excitement, depression, spastic colon)

    Muscarine Poisoning: Ingestion of any number of Inocybe or Clitocybe species (e.g., Inocybe geophylla, Clitocybe dealbata) results in an illness characterized primarily by profuse sweating. This effect is caused by the presence in these mushrooms of high levels (3- 4%) of muscarine. Muscarine poisoning is characterized by increased salivation, perspiration, and lacrimation within 15 to 30 minutes after ingestion of the mushroom. With large doses, these symptoms may be followed by abdominal pain, severe nausea, diarrhea, blurred vision, and labored breathing. Intoxication generally subsides within 2 hours. Deaths are rare, but may result from cardiac or respiratory failure in severe cases.

    Ibotenic acid/Muscimol Poisoning: The Fly Agaric (Amanita muscaria) and Panthercap (Amanita pantherina) mushrooms both produce ibotenic acid and muscimol. Both substances produce the same effects, but muscimol is approximately 5 times more potent than ibotenic acid. Symptoms of poisoning generally occur within 1 - 2 hours after ingestion of the mushrooms. An initial abdominal discomfort may be present or absent, but the chief symptoms are drowsiness and dizziness (sometimes accompanied by sleep), followed by a period of hyperactivity, excitability, illusions, and delirium. Periods of drowsiness may alternate with periods of excitement, but symptoms generally fade within a few hours. Fatalities rarely occur in adults, but in children, accidental consumption of large quantities of these mushrooms may cause convulsions, coma, and other neurologic problems for up to 12 hours.

    Psilocybin Poisoning: A number of mushrooms belonging to the genera Psilocybe, Panaeolus, Copelandia, Gymnopilus, Conocybe, and Pluteus, when ingested, produce a syndrome similar to alcohol intoxication (sometimes accompanied by hallucinations). Several of these mushrooms (e.g., Psilocybe cubensis, P. mexicana, Conocybe cyanopus) are eaten for their psychotropic effects in religious ceremonies of certain native American tribes, a practice which dates to the pre- Columbian era. The toxic effects are caused by psilocin and psilocybin. Onset of symptoms is usually rapid and the effects generally subside within 2 hours. Poisonings by these mushrooms are rarely fatal in adults and may be distinguished from ibotenic acid poisoning by the absence of drowsiness or coma. The most severe cases of psilocybin poisoning occur in small children, where large doses may cause the hallucinations accompanied by fever, convulsions, coma, and death. These mushrooms are generally small, brown, nondescript, and not particularly fleshy; they are seldom mistaken for food fungi by innocent hunters of wild mushrooms. Poisonings caused by intentional ingestion of these mushrooms by people with no legitimate religious justification must be handled with care, since the only cases likely to be seen by the physician are overdoses or intoxications caused by a combination of the mushroom and some added psychotropic substance (such as PCP).
  • Gastrointestinal irritants (compounds that produce rapid, transient nausea, vomiting, abdominal cramping, and diarrhea)
    Numerous mushrooms, including the Green Gill (Chlorophyllum molybdites), Gray Pinkgill (Entoloma lividum), Tigertop (Tricholoma pardinum), Jack O'Lantern (Omphalotus illudens), Naked Brimcap (Paxillus involutus), Sickener (Russula emetica), Early False Morel (Verpa bohemica), Horse mushroom (Agaricus arvensis) and Pepper bolete (Boletus piperatus), contain toxins that can cause gastrointestinal distress, including but not limited to nausea, vomiting, diarrhea, and abdominal cramps. In many ways these symptoms are similar to those caused by the deadly protoplasmic poisons. The chief and diagnostic difference is that poisonings caused by these mushrooms have a rapid onset, rather than the delayed onset seen in protoplasmic poisonings. Some mushrooms (including the first five species mentioned above) may cause vomiting and/or diarrhea which lasts for several days. Fatalities caused by these mushrooms are relatively rare and are associated with dehydration and electrolyte imbalances caused by diarrhea and vomiting, especially in debilitated, very young, or very old patients. Replacement of fluids and other appropriate supportive therapy will prevent death in these cases. The chemistry of the toxins responsible for this type of poisoning is virtually unknown, but may be related to the presence in some mushrooms of unusual sugars, amino acids, peptides, resins, and other compounds.
  • Disulfiram-like toxins  [These are generally nontoxic and produce no symptoms unless alcohol is consumed within 72 hours after eating them, in which case a short-lived acute toxic syndrome is produced.]
    The Inky Cap Mushroom (Coprinus atramentarius) is most commonly responsible for this poisoning, although a few other species have also been implicated. A complicating factor in this type of intoxication is that this species is generally considered edible (i.e., no illness results when eaten in the absence of alcoholic beverages). The mushroom produces an unusual amino acid, coprine, which is converted to cyclopropanone hydrate in the human body. This compound interferes with the breakdown of alcohol, and consumption of alcoholic beverages within 72 hours after eating it will cause headache, nausea and vomiting, flushing, and cardiovascular disturbances that last for 2 - 3 hours.
Miscellaneous Poisonings: Young fruiting bodies of the sulfur shelf fungus Laetiporus sulphureus are considered edible. However, ingestion of this shelf fungus has caused digestive upset and other symptoms in adults and visual hallucinations and ataxia in a child.
TYPES OF TOXINSSPECIES OF POISONOUS MUSHROOMS
1. Cyclopeptides, e.g., AmanitoxinsAmanita phalloides, Amanita verna, Amanita virosa, Galerina autumnalis, Galerina marginata and Conocybe filaris
2. Gyromitrin, e.g., Monomethylhydrazine (MMH)Gyromitra esculenta, Gyromitra infula, and species of Helvella and Paxina
3. OrellanineCortinarius orellanus, Cortinarius speciosissimus, Cortinarius splendens
4. MuscarineClitocybe and Inocybe
5. Ibotenic Acid, MuscimolAmanita cokeri, Amanita gemmata, Amanita muscaria and Amanita pantherina and Panaeolus campanulatus
6. Coprine (Anabuse-like Reaction)Coprinus atramentarius
7. Psilocybin and PsilocinPsilocybe, Panaeolus, Conocybe  and Gymnopilus
8. Gastrointestinal irritant, composed of a number of unrelated compounds, which produce similar effectsAgaricus, Amanita, Boletus, Chlorophyllum, Entoloma, Hebeloma, Lactarius, Marasmius, Naematoloma, Russula, Scleroderma, Tricholoma and many others

Follow these five rules to avoid mushroom poisoning:

  • Identify each and every mushroom you collect, and only eat those whose identification you are sure of. When in doubt, throw it out.
  • Strictly avoid: any mushroom that looks like an amanita (parasol-shaped mushrooms with white gills); all little brown mushrooms; all false morels.
  • Some people are allergic to even the safest mushrooms. The first time you try a new wild mushroom, it is important that you eat only a small amount and wait 24 hours before eating more.
  • As with other foods, rotting mushrooms can make you ill. Eat only firm, fresh, undecayed mushrooms.
  • Most wild mushrooms should not be eaten raw or in large quantities, since they are difficult to digest.