Numerous mushroom species cause toxicity when ingested. Toxins and thus symptoms vary by species. Identification of specific species is difficult, so treatment usually is guided by symptoms.
(See also General Principles of Poisoning.)
Differentiating toxic and nontoxic species in the wild is difficult, even for highly knowledgeable people. Folklore rules are unreliable, and the same species may have varying degrees of toxicity depending on where and when they are harvested. If patients have eaten an unidentified mushroom, identifying the species can help determine specific treatment. However, because an experienced mycologist is seldom available for immediate consultation, treatment of patients who become ill after mushroom ingestion is usually guided by symptoms. If a sample of the mushroom, uningested or from the patient’s emesis, is available, it can be sent to a mycologist for analysis.
All toxic mushrooms cause vomiting and abdominal pain; other manifestations vary significantly by mushroom type. Generally, mushrooms that cause symptoms early (within 2 hours) are less dangerous than those that cause symptoms later (usually after 6 hours).
Amanita species, but none have shown consistently positive results.
Early gastrointestinal (GI) symptoms
Mushrooms that cause early GI symptoms (eg, Chlorophyllum molybdites and the little brown mushrooms that often grow in lawns) cause gastroenteritis, sometimes with headaches or myalgias. Diarrhea is occasionally bloody.
Symptoms usually resolve within 24 hours.
Treatment is supportive.
Early neurologic symptoms
Mushrooms that cause early neurologic symptoms include hallucinogenic mushrooms, which are usually ingested recreationally because they contain psilocybin, a hallucinogen. The most common are members of the Psilocybe genus, but some other genera contain psilocybin.
Symptoms begin within 15 to 30 minutes and include euphoria, enhanced imagination, and hallucinations. Tachycardia and hypertension are common, and hyperpyrexia occurs in some children; however, serious consequences are rare.
Treatment occasionally involves sedation (eg, with benzodiazepines).
Early muscarinic symptoms
Certain mushrooms contain toxins that stimulate muscarinic cholinergic receptors, thus mimicking the effects of acetylcholine on these receptors (the toxins do not stimulate nicotinic cholinergic receptors). Mushrooms that cause early muscarinic symptoms include members of the Inocybe and Clitocybe genera.
Symptoms may include the SLUDGE syndrome (see table Common Toxic Syndromes), including miosis, bronchorrhea, bradycardia, diaphoresis, wheezing, and cramps. Symptoms are usually mild, begin within 30 minutes, and resolve within 12 hours.
Delayed GI symptoms
Mushrooms that cause delayed GI symptoms include members of the Amanita, Gyromitra, and Cortinarius genera.
The most toxic Amanita mushroom is Amanita phalloides, which causes 95% of mushroom poisoning deaths. Initial gastroenteritis, which may occur 6 to 12 hours after ingestion, can be severe; hypoglycemia can occur. Initial symptoms abate for a few days; then liver failureliver transplantation; other specific treatments (eg, N
Amanita smithiana mushrooms cause delayed gastroenteritis, usually 6 to 12 hours after ingestion, and acute renal failure (usually within 1 to 2 weeks after ingestion) that often requires dialysis.
Gyromitra mushrooms can cause hypoglycemia simultaneously with or shortly after gastroenteritis
Most Cortinarius mushrooms are indigenous to Europe. Gastroenteritis may last for 3 days. Renal failure, with symptoms of flank pain and decreased urine output, may occur 3 to 20 days after ingestion. Renal failure often resolves spontaneously, but dialysis may be required for a brief period if renal function does not improve in 3 to 5 days and chronic renal damage may be permanent.
Delayed muscular symptoms
Several mushroom species cause a delayed myotoxicity with resultant rhabdomyolysis that is sometimes fatal. Tricholoma spp can cause fatigue, muscle weakness, myalgias, and rhabdomyolysis 24 to 72 hours after ingestion. Russula spp have caused similar myotoxicity affecting myocardial tissue resulting in tachycardia, hypotension, arrhythmias, and death. There is no specific treatment other than supportive care.
Delayed neurologic syndromes
Some Clitocybe mushrooms cause erythromelalgia, which is paresthesias and severe burning dysesthesias with edema and erythema of the distal extremities, 24 hours after ingestion. IV nicotinic acid may be an effective treatment.
Hapalopilus rutilans causes a delayed (more than 12 hours after ingestion) central nervous system syndrome of vertigo, ataxia, visual disturbances, somnolence, and encephalopathy.
Pleurocybella porrigens causes a delayed (between 1 to 31 days) syndrome of altered consciousness, convulsions, myoclonus, dysarthria, encephalopathy, respiratory failure and death.
