[/sidebar]

Ibotenic Acid/Muscimol

Mushrooms containing these compounds are most commonly found in the Amanita sp., with the noted exclusion of Amanita phalloides (addressed later). They contain ibotenic acid and its metabolite, muscimol, which act in vivo like glutamic acid and GABA, respectively. Onset of symptoms is typically rapid, within 2 hours, and may produce hallucinations, dysphoria, and delirium. In children, symptoms may include seizures and myoclonus. Treatment is supportive, there are no delayed ill effects, and symptomatically controlled patients may be discharged.

Muscarine

Clitocybe and Inocybe sp. are the representative members of this toxicologic group, and predictable peripheral muscarinic effects predominate (see sidebar for the DUMBBELS mnemonic). Though atropine would be the drug of choice for symptomatic control, it is rarely needed. Symptoms develop rapidly, within 2 hours, but may persist for hours more as well. Again, symptomatically controlled patients are safe for discharge.

Psilocybin

Likely the most recognizable mushroom by name, it is also the most common identifiable mushroom to be ingested year after year.¹ Psilocybe sp. mushrooms contain the indole psilocybin, which mimics the action of serotonin in the brain. Hallucinations, which are often the intended purpose of mushroom ingestion, are common, as are tachycardia, hypertension, hyperthermia, and diaphoresis. In fact, these clinical effects may precede the hallucinations in some cases.

While psilocybin has some similarities to lysergic acid diethylamide (LSD), severe effects such as coma, malignant hyperthermia, and death have been documented only once in mushroom ingestion.⁶ Effects are very rapid, and often only reassurance is needed. However, benzodiazepines also may offer some relief. Discharge is appropriate once vital signs normalize.

Gastrointestinal Toxins

The majority of mushroom ingestions that present to health care facilities do cause some gastrointestinal (GI) upset. Multiple species are responsible for this phenomenon, and onset of nausea, vomiting, and abdominal pain rapidly follows ingestion, usually in less than 3 hours. Patients may divulge a history of foraging for edible brown mushrooms, or may admit to searching for hallucinogenic mushrooms. Care is symptomatic, and some patients may present fairly dehydrated. Disposition is similar to that in other causes of gastroenteritis.

A special case, the Paxillus sp. mushroom, merits mention in this class as well. While Paxillus sp. cases present as do other mushrooms with predominantly gastrointestinal effects, it can also cause hemolytic anemia and renal failure. Syndromic classification systems have missed this potential morbidity in the past.⁵ In patients with severe GI symptoms requiring admission, it may be useful to evaluate a blood count, metabolic panel, and urinalysis to rule out this syndrome.