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Mushroom Poisoning

by Gerald F. O’Malley, DO, Rika O’Malley, MD

Numerous mushroom species cause toxicity when ingested. Symptoms vary by species. Identification of specific species is difficult, so treatment usually is guided by symptoms.

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 h) are less dangerous than those that cause symptoms later (usually after 6 h). Activated charcoal may be useful to limit absorption.

Early 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 h. 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 min 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

Mushrooms that cause early muscarinic symptoms include members of the Inocybe and Clitocybe genera.

Symptoms may include the SLUDGE syndrome (see Common Toxic Syndromes (Toxidromes)), including miosis, bronchorrhea, bradycardia, diaphoresis, wheezing, and fasciculations. Symptoms are usually mild, begin within 30 min, and resolve within 12 h.

Atropine may be given to treat severe muscarinic symptoms (eg, wheezing, bradycardia).

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 h after ingestion, can be severe; hypoglycemia can occur. Initial symptoms abate for a few days; then liver failure and sometimes renal failure develop. Initial care involves close monitoring for hypoglycemia and possibly repeated doses of activated charcoal. Treatment of liver failure may require liver transplantation; other specific treatments (eg, N -acetylcysteine, high-dose penicillin, silibinin, IV fat emulsion) are unproved.

Amanita smithiana mushrooms cause delayed gastroenteritis, usually 6 to 12 h after ingestion, and acute renal failure (usually within 1 to 2 wk after ingestion) that often requires dialysis.

Gyromitra mushrooms can cause hypoglycemia simultaneously with or shortly after gastroenteritis. Other manifestations may include CNS toxicity (eg, seizures) and, after a few days, hepatorenal syndrome. Initial care involves close monitoring for hypoglycemia and possibly repeated doses of activated charcoal. Neurologic symptoms are treated with pyridoxine 70 mg/kg slow IV infusion over 4 to 6 h (maximum daily dose of 5 g); liver failure is treated supportively.

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.

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