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  • Updated 05.14.2024
  • Released 09.10.2021
  • Expires For CME 05.14.2027

Hallucinogenic mushroom intoxication and poisoning



Hallucinogenic mushroom poisoning is the most common neurotoxic presentation of mushroom toxicity. Two main toxidromes associated with hallucinogenic mushroom poisoning are related to the responsible toxin: the psilocybin toxidrome and the muscimol/ibotenic acid toxidrome. Hallucinogenic mushroom toxins produce their associated toxidromes by selectively affecting neurotransmission. Psilocybin and psilocin have serotonergic properties, whereas muscimol is a potent, selective agonist for the GABAA receptors and binds to the same site on the GABAA receptor complex as GABA itself.

Magic mushrooms continue to be fashionable among drug users, especially young drug users, in part because they are often believed to be relatively harmless compared to other hallucinogenic drugs. However, serious adverse outcomes have been reported, including myocardial infarction; severe rhabdomyolysis, acute renal failure, and posterior encephalopathy; and protracted paranoid psychosis. Ingestion of magic mushrooms may result in horror trips combined with self-destructive and suicidal behavior, especially among people with mental or psychiatric disorders (34; 22). Serious and often permanent organ dysfunction or fatalities may result from accidentally ingesting a more toxic mushroom resembling one that is hallucinogenic (eg, mushrooms of the genus Cortinarius, which are nephrotoxic).

No particular diagnostic procedures are available or needed for most patients with hallucinogenic mushroom toxicity. Care of patients with hallucinogenic mushroom poisoning is primarily supportive and symptomatic. Most patients with hallucinogenic mushroom toxicity can be treated without medications. Seizures are uncommon with hallucinogenic mushroom poisoning, except in young children. The vast majority of poisoned individuals recover without serious permanent morbidity. However, uncommon fatalities and serious adverse outcomes do occur and include suicide, protracted psychosis, and myocardial infarction.

Key points

• Management of hallucinogenic mushroom poisoning is primarily supportive and symptomatic.

• Hallucinogenic mushroom toxins produce their associated toxidromes by affecting neurotransmission.

• Hallucinogenic mushroom poisoning is rarely fatal.

• Other serious and often permanent organ dysfunction or fatalities may result from accidentally ingesting a more toxic mushroom resembling one that is hallucinogenic.

Historical note and terminology

Basidiomycota are filamentous fungi composed of hyphae and reproduce sexually. Basidiomycota include inter alia some fungi that might be grown or foraged for food (eg, mushrooms, puffballs, bracket fungi, other polypores, and chanterelles) and fungi that infest plants and might be secondarily ingested (eg, smuts, bunts, rusts). The toxidromes associated with fungi of the phylum Basidiomycota include forms of hallucinogenic mushroom poisoning. With hallucinogenic mushrooms ("magic mushrooms" or "shrooms"), exposure to the fungal toxins is generally intentional, whereas the exposure is generally accidental with other forms of mushroom poisoning.

Hallucinogenic mushroom poisoning. Hallucinogenic mushroom poisoning is the commonest neurotoxic presentation of mushroom toxicity.

Psilocybin-containing mushrooms have been used in indigenous New World cultures in religious, divinatory, or spiritual contexts for millennia (35; 42). They are represented in the Pre-Columbian sculptures and glyphs seen throughout North, Central, and South America.

Religious statues involving Psilocybe mushrooms

Various "mushroom stones" created from 1000 BCE to 500 CE. Stones measure approximately 1 foot tall. (Public domain. Edited using Photoshop CS6 and enlarged using the artificial intelligence software Topaz Gigapixel AI by Dr Do...

In 1800, Everard Brande first reported hallucinogenic mushroom poisoning in the Western medical literature: the disorder affected a father and four of his children, in varying degrees, as a function of age and quantity ingested (dose-response effect) (06). The portion of the report dealing with one child is abstracted below:

J.S. gathered early in the morning of the third of October [1799], in the Green Park [in London], what he supposed to be small mushrooms; these he stewed with the common additions in a tinned iron saucepan. The whole did not exceed a tea saucerful, which he and four of his children ate the first thing, about eight o'clock in the morning, as they frequently had done without any bad consequence; they afterwards took their usual breakfast of tea, & c. which was finished about nine, when Edward, one of the children (eight years old), who had eaten a large proportion of the mushrooms, as they thought them, was attacked with fits of immoderate laughter, nor could the threats of his father or mother restrain him. To this succeeded vertigo, and a great degree of stupor, from which he was roused by being called or shaken, but immediately relapsed. The pupils of his eyes were, at times, dilated to nearly the circumference of the cornea, and scarcely contracted at the approach of a strong light; his breathing was quick, his pulse very variable, at times imperceptible, at others too frequent and small to be counted; latterly, very languid; his feet were cold, livid, and contracted; he sometimes pressed his hands on different parts of his abdomen, as if in pain, but when roused and interrogated as to it, he answered indifferently, yes, or no, as he did to every other question, evidently without any relation to what was asked. ... By four o'clock every violent symptom had left him, drowsiness and occasional giddiness only remaining, both of which, with some head-ach, continued during the following day.

These mushrooms were later identified as Psilocybe semilanceata ("liberty cap"). Its popular name is based on its resemblance to a Phrygian cap or liberty cap, which is emblematic of a slave's manumission (release from slavery) in classical antiquity. Such a cap is incorporated into the seal of the United States Senate and is portrayed in many iconic images of the national personification symbols of Liberty for the United States and of Marianne for the French Republic since the French Revolution, with similar representations in many other countries. In the 1960s, this species was found to contain the hallucinogenic compound psilocybin.

Psilocybe semilanceata (“liberty cap”) mushroom

In the 1960s, this species was found to contain the hallucinogenic compound psilocybin. (Public domain. Cropped from original.)

Lewis Carroll. English author, poet, and mathematician Charles Lutwidge Dodgson (1832–1898) is better known by his pen name: Lewis Carroll. His most notable works are Alice's Adventures in Wonderland (1865) and its sequel Through the Looking-Glass (1871).

English author, poet, and mathematician Charles Lutwidge Dodgson (1832–1898) is better known by his pen name: Lewis Carroll

Photographic self-portrait, taken June 2, 1857, around the time that Carroll drafted the stories that made him famous. This photograph was first published in Carroll's biography by his nephew, Stuart Dodgson Collingwood. (Sourc...

In the late 1850s, Dodgson became friends with the family of the new Dean of Christ Church, Henry George Liddell (1811–1898). Dodgson grew into the habit of taking the Liddell children on rowing trips accompanied by an adult friend. On one such excursion in 1862, Dodgson developed the outline of a story that he told to one of the children, Alice Liddell, and she begged him to write it down. Dodgson eventually presented her with a handwritten, illustrated manuscript entitled Alice's Adventures Under Ground in November 1864 as "A Christmas gift to a Dear Child in Memory of a Summer Day." The original illustrations were by Dodgson, and even though these do not compare to the later iconic images of Sir John Tenniel (1820–1914), they do give a sense of what Carroll had in mind for what were later interpreted to be hallucinogenic experiences. Of most relevance here was Alice's meeting with the hookah-smoking blue caterpillar on top of a mushroom.

Alice looked all round her at the flowers and the blades of grass, but could not see anything that looked like the right thing to eat under the circumstances. There was a large mushroom near her... She stretched herself up on tiptoe, and peeped over the edge of the mushroom and her eyes immediately met those of a large blue caterpillar, which was sitting with its arms folded, quietly smoking a long hookah, and taking not the least notice of her or of anything else (Carroll 1864).

Later, the caterpillar and Alice discussed what size she wanted to be:

[I]n a few minutes the caterpillar took the hookah out of its mouth, and got down off the mushroom, and crawled away into the grass, merely remarking as it went: "the top will make you grow taller, and the stalk will make you grow shorter." "The top of what? the stalk of what [?"] thought Alice. "Of the mushroom," said the caterpillar, just as if she had asked it aloud, and in another moment it was out of sight.

Alice remained looking thoughtfully at the mushroom for a minute, and then picked it and carefully broke it in two, taking the stalk in one hand, and the top in the other. "Which does the stalk do?" she said and nibbled a little bit of it to try: the next moment she felt a violent blow on her shin: it had struck her foot!

She was a good deal frightened by this very sudden change, but as she did not shrink any further, and had not dropped the top of the mushroom, she did not give up hope yet. There was hardly room to open her mouth, with her chin pressing against her foot, but she did it at last, and managed to bite off a little bit of the top of the mushroom.

"Come! my head's free at last!" said Alice in a tone of delight, which changed into alarm in another moment, when she found that her shoulders were nowhere to be seen: she looked down upon an immense length of neck, which seemed to rise like a stalk out of a sea of green leaves that lay far below her.

Dodgson's manuscript was ultimately published as Alice's Adventures in Wonderland in 1865 under the Lewis Carroll pen name. In Alice's Adventures in Wonderland, as in the earlier manuscript, Alice tried portions of the stalk and cap of a mushroom and subsequently experienced distortions of her body image (08; 10). This phenomenon of self-experienced paroxysmal body image illusions involving distortions of the size, mass, or shape of the body or its position in space, often occurring with depersonalization and derealization, was later incorporated into English psychiatrist John Todd’s description of Alice in Wonderland syndrome in 1955 (44; 28; 27). Although there is no evidence that Dodgson ever tried hallucinogenic mushrooms, he did take belladonna alkaloids--plant-derived anticholinergic agents that have "deliriant" and hallucinogenic potential—for his insomnia and migraine (23). Apparently, he was also aware of accounts of the hallucinogenic effects of Siberian fly agaric mushrooms (23).

The seeming references to hallucinogenic mushroom ingestion in Alice's Adventures in Wonderland (1865) were revisited a century later. For example, "White Rabbit" is an Alice in Wonderland-inspired song written by Grace Slick, reportedly after a drug-induced "trip" (ie, during a temporary altered state of consciousness induced by consumption of a hallucinogenic substance, most commonly LSD, mescaline, or psilocybin mushrooms). The song specifically references hallucinatory experiences after ingesting "some kind of mushroom" and refers to the similar experiences of "Alice," the protagonist of Lewis Carroll's fantasy works (08; 09; 10):

When men on the chessboard
Get up and tell you where to go
And you've just had some kind of mushroom
And your mind is moving slow
Go ask Alice, I think she'll know

Lyrics from “White Rabbit” by Grace Slick of the American rock band Jefferson Airplane for their 1967 album Surrealistic Pillow.

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