Toxic Fungi of Western North America

by Thomas J. Duffy, MD

Guide to the identification of mushroom poisoning by symptoms

The latency (delay from eating the mushroom to first symptom) in the list below varies considerably. Early onsets with GI symptoms reported for toxins normally having long latency periods suggests that the mushrooms have been spoiled or eaten with other mushrooms that have early GI effects. Not all symptoms listed need occur in any one patient. Some of the mushrooms associated with a long latency period occasionally produce early gastrointestinal symptoms in some persons, but not in others. These early symptoms may be due to compounds other than the primary toxin or may represent a biphasic response to the primary toxin in susceptible patients.

Onset of symptoms less than 4 hours after ingestion:

  1. Nausea, vomiting, diarrhea, abdominal cramping with no progression beyond GI involvement—GI toxins, irritants and idiosyncrasies. A few GI symptoms are delayed. See #6 in the next paragraph (onset over 4 to 14 hours from ingestion). (17b) (many species)
  2. Drowsiness, ataxia, occasional nausea, obtundation (may alternate with hyperkinetc states), muscle fasciculation, seizures. Ibotenic acid in children.
  3. Nausea, confusion, ataxia, feelings of increased strength or euphoria, muscle fasciculation, sensations of floating or color changes, rarely progressing to coma or seizures as in children. Ibotenic acid in adults. (Amanita muscaria, Amanita pantherina complex)
  4. Nausea, vomiting, diarrhea (usually starting in 1-4 hours); progressing to severe malaise, weakness, sweating, cold extremities, confusion, cardiovascular collapse or coma associated with autoimmune hemolysis and damage to kidney and other major organs. There is usually a history of earlier ingestions without symptoms. Autoimmune hemolysis. (Paxillus involutus).
  5. GI symptoms at 4 hours rarely, usually a more delayed onset. Associated kidney failure. See Amanita smithiana below (#5 of “onset of symptoms after 4 hours from time of ingestion”).
  6. GI symptoms, usually by 4 hours along with hemolysis—in association with the ingestion of raw or poorly cooked mushrooms, especially amanitas. Particularly suspect are “blushers” such as Amanita novinupta and those amanitas referred to the European name Amanita franchetii (Boud.) Fayod.
  7. Euphoria, occasional panic reactions, hallucinations, dilated pupils and rarely nausea to the point of vomiting. Look for seizures, fever in children. Psilocybin. (Psilocybe, other dark spored genera)
  8. Sweating, salivation, nausea, teary eyes with dilated pupils, slow heart rate and sometimes diarrhea and increased urination. Large ingestions may cause pulmonary edema and seizures. Muscarine. (Clitocybe & Inocybe)
  9. Within 5-30 minutes of taking alcohol after ingestion of the offending mushroom, the occurrence of flushing, throbbing in the temples, headache, fast heart rate and occasionally nausea and vomiting. Symptoms may recur after alcohol consumption for up to 3 days, but are less severe over time. Coprine. (Coprinus)
  10. Rare onset at 1-4 hours of malaise, vomiting, headache, dizziness usually occurring after 6 hours—see gyromitrin below.
  11. Malaise, GI symptoms, severe headache, generalized aching, flushing, incoordination, muscular weakness, difficulty walking and confusion. One hour after ingestion (2 cases). Poisoning with Stropharia coronilla.

Onset of symptoms after 4 hours from time of ingestion:

  1. Sudden malaise, GI symptoms and often severe headache & dizziness at 2-25 hours after ingestion of “false morels”. The latency period, which is most commonly 6-12 hours, has been reported as late as 40 hours. Symptoms may progress to muscle cramps, shock, methemoglobinuria, liver failure, fever and CNS symptoms including convulsions. Hemolysis, hemoglobinuria and kidney failure are uncommon. Gyromitrin. (Gyromitra, Helvella; other ascomycetes?)
  2. Diarrhea, nausea, vomiting, abdominal cramping, malaise usually at 10-16 hours (rarely 5-36 hours) after ingestion progressing to liver failure and rarely kidney failure with decreased urine, shock, acidosis etc. (if severe renal failure, consider alternatives such as 3, 4 & 5 below or a novel toxin) Amanitin. (Amanita phalloides, Amanita ocreata etc.)
  3. Diarrhea, nausea, vomiting 4-10 hours after ingestion (reports range from 5-9 hours) with elevated blood liver enzymes and rare progression to liver failure associated with a description of yellow brown mushrooms clumped on living trees or dead stumps. No North American cases yet reported, although this species is common both in Europe and North America. Poisoning with Hypholoma fasciculare.
  4. GI symptoms sometimes at 4-12 hours (18) with much later burning and dryness of the mouth at 2 days to 5 weeks progressing to severe thirst, frequent urination of an increased quantity of dilute urine; later having reduced quantity of urine and kidney failure. Cortinarius rubellus Cooke. [Poisonings have not clearly occurred in Western North America, although a few reports are suggestive of its bipyridyl toxins. (19)]
  5. GI symptoms at 4-12 hours followed by kidney failure. (One case of liver failure.) Further characterization of the syndrome and the pathological findings are needed. Collection of ±white mushrooms including presumed matsutake. Amanita smithiana Bas.
  6. GI symptoms only, but having latencies as long as 4-14 hours on occasion—for example, the vase-shaped Gomphus floccosus, kauffmanii and bonarii. Other species such as those in the Armillaria mellea complex and some boletes have also had delayed symptoms in Europe. (17b)