is it considered to be poisonous?
Yes, it can be poisonous if ingested.
Amanita muscaria
"Amanita muscaria" poisoning has occurred in young children and in people who ingested the mushrooms for a hallucinogenic experience.
what is the red mushroom with white dots Amanita muscaria how did it get its name? The name in many European languages is thought to derive from its use as an insecticide when sprinkled in milk. Its scientific name was, however, given by Linnaeus and Lamarck.
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Amanita muscaria [SEP] Toxicity
"Amanita muscaria" poisoning has occurred in young children and in people who ingested the mushrooms for a hallucinogenic experience. Occasionally it has been ingested in error, because immature button forms resemble puffballs. The white spots sometimes wash away during heavy rain and the mushrooms then may appear to be the edible "A. caesarea". "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; this is typically about the amount found in one cap of "Amanita muscaria".