(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).
Treatment for most mushroom poisonings is symptomatic and supportive. Activated charcoal may be useful to limit absorption. Numerous antidotal therapies have been tried, especially for Amanita species, but none have shown consistently positive results.
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).
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 fasciculations. Symptoms are usually mild, begin within 30 minutes, and resolve within 12 hours.
Atropine may be given to treat severe muscarinic symptoms (eg, wheezing, bradycardia).
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 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 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. Other manifestations may include central nervous system 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 hours (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.