Amanita muscaria poisoning has occurred in young children and in people who ingested the mushrooms for a hallucinogenic experience.[15][44][45] Occasionally it has been ingested in error, because immature button forms resemble puffballs.[46] The white spots sometimes wash away during heavy rain and the mushrooms then may appear to be the edible A. caesarea.[47]
Amanita muscaria contains several biologically active agents, at least one of which, muscimol, is known to be psychoactive. Ibotenic acid, a neurotoxin, serves as a prodrug to muscimol, with approximately 10–20% converting to muscimol after ingestion. An active dose in adults is approximately 6 mg muscimol or 30 to 60 mg ibotenic acid;[48][49] this is typically about the amount found in one cap of Amanita muscaria.[50] The amount and ratio of chemical compounds per mushroom varies widely from region to region and season to season, which can further confuse the issue. Spring and summer mushrooms have been reported to contain up to 10 times more ibotenic acid and muscimol than autumn fruitings.[44]
A fatal dose has been calculated as 15 caps.[51] Deaths from this fungus A. muscaria have been reported in historical journal articles and newspaper reports,[52][53][54] but with modern medical treatment, fatal poisoning from ingesting this mushroom is extremely rare.[55] Many older books list Amanita muscaria as "deadly", but this is an error that implies the mushroom is more toxic than it is.[56] The North American Mycological Association has stated that there were "no reliably documented cases of death from toxins in these mushrooms in the past 100 years".[57]
The active constituents of this species are water-soluble, and boiling and then discarding the cooking water at least partly detoxifies A. muscaria.[58] Drying may increase potency, as the process facilitates the conversion of ibotenic acid to the more potent muscimol.[59] According to some sources, once detoxified, the mushroom becomes edible.[60][61]
