Does Amanita muscaria contain muscarine, and does it matter? It does contain it, and the compound is literally named after the mushroom. Muscarine was isolated from fly agaric in 1869, the first mushroom toxin ever identified. For a century it was blamed for the mushroom's effects, until chemists showed the real actors were ibotenic acid and muscimol. Now a 2025 study suggests textbooks went too far the other way, and that muscarine may explain some of fly agaric's unpleasant side effects.
Muscarine is in Amanita muscaria, but it isn't what produces the mushroom's main effects; ibotenic acid and muscimol are. For decades the accepted muscarine level was a trace 0.0003% of fresh weight. A 2025 analysis measured 0.004–0.043%, and a survey of 53 people found sweating, salivation and similar cholinergic symptoms at commonly used amounts of 1–20 g dried (Feeney 2025). Mushrooms such as Inocybe and Clitocybe carry far more, and those cause true muscarine poisoning.
For the compounds that do drive fly agaric's effects, see our ibotenic acid versus muscimol guide and the overview of fly agaric's chemical composition.
What Is Muscarine?
Muscarine is a small, water-soluble molecule that mimics acetylcholine, the nerve signal behind "rest and digest" functions. It switches on muscarinic receptors in glands, the gut, the heart and the eye. The receptors are named after the compound, which is named after the mushroom.
Its effects are easy to predict once you know the system. More muscarinic activity means more sweat, saliva and tears, a slower heart, narrowed pupils, stomach cramps and diarrhoea. Doctors summarise it as a cholinergic toxidrome.
One detail explains a lot. Muscarine carries a permanent electrical charge, which keeps it from crossing into the brain easily. So it acts mostly on the body, not the mind. That's a first clue it can't account for fly agaric's dreamlike effects.
Why Was It Blamed for Fly Agaric's Effects?
Because it was found first. Pharmacologists isolated muscarine from fly agaric in 1869, and it became the first mushroom toxin ever identified (Rubel and Arora 2008). For almost a century, it was assumed to be the active principle.
That changed in the 1960s, when Japanese, British and Swiss chemists identified ibotenic acid and muscimol. Muscimol acts on GABA-A receptors in the brain, and it matches what people actually report: drowsiness, altered perception and deep sleep. Muscarine was demoted to a footnote.
The footnote got a number. A 1950s measurement put muscarine in fresh fly agaric at about 0.0003%, a level too low to matter. That figure was repeated for decades, and it's why most sources still say fly agaric's muscarine is clinically irrelevant.
What Did the 2025 Study Find?
Far more muscarine than the old figure. Kevin Feeney and colleagues analysed fly agaric samples by HPLC-MS/MS, a modern mass-spectrometry method. They found muscarine from 0.004% up to 0.043%, well above the old consensus value (Feeney 2025). The old figure was for fresh mushrooms, and fresh caps are mostly water, so the two numbers aren't directly comparable. Even allowing for that, the upper end is many times higher.
The team also surveyed 53 people who'd had cholinergic symptoms after eating fly agaric. Those symptoms appeared at amounts that reflect common use, 1 to 20 g dried. The authors concluded that muscarine in fly agaric runs across a broad range, from insignificant to physiologically significant.
Does that overturn the textbooks? Not entirely. Ibotenic acid and muscimol remain the drivers of the main effects. What changes is the side-effect picture. Sweating and drooling after fly agaric may not be imagination or impurity. They may be muscarine, in some batches.
Is Fly Agaric Poisoning a Muscarine Poisoning?
Usually not. Real muscarine poisoning comes from other mushrooms, mainly fibrecaps (Inocybe) and some small white funnel caps (Clitocybe). Those carry far more muscarine, and the result is a classic cholinergic picture. In a 2023 Hong Kong case, two patients developed vomiting, diarrhoea, small pupils, palpitations and sweating after eating wild mushrooms, and muscarine was confirmed in their urine (Chan 2023).
Even in those mushrooms, the chemistry is subtler than it looks. A 2024 German study found that in lab-grown mycelium of one Clitocybe species, the main compound was a phosphorylated form of muscarine with weak activity. Enzymes can convert it into muscarine when tissue is damaged (Dörner 2024). Measured toxin levels can therefore understate what a damaged or eaten mushroom releases.
Fly agaric poisoning tends to look different. In Polish hospital data, symptoms were mainly vomiting, hallucinations, restlessness and central nervous system depression. A few patients had a fast heart rate, dilated pupils and dry, red skin, which is closer to the opposite of a muscarine picture (Łukasik-Głębocka 2011).
| Feature | Muscarine poisoning (Inocybe, Clitocybe) | Typical fly agaric poisoning |
|---|---|---|
| Main compounds | Muscarine | Ibotenic acid, muscimol |
| Key signs | Sweating, salivation, small pupils, slow heart, cramps | Confusion, agitation or drowsiness, hallucinations, sleep |
| Brain involvement | Limited | Central |
| Cholinergic signs | Defining | Sometimes, and possibly batch-dependent |
The treatment differs too. Doctors counter heavy muscarine poisoning with atropine, which blocks muscarinic receptors (Patocka 2021). That's not routine for fly agaric, where symptoms are mostly central. It's one reason poison centres want to know exactly which mushroom was eaten.
How Do Labs Measure Muscarine Today?
With methods far more sensitive than those available in the 1950s. Modern labs use liquid chromatography or capillary electrophoresis coupled to tandem mass spectrometry. A Czech method published in 2014 measures ibotenic acid, muscimol and muscarine together in a single run, down to nanomolar levels in urine (Ginterová 2014).
That matters for two reasons. First, it lets researchers revisit old numbers, which is exactly what Feeney's team did. Second, it means poison centres can confirm which compounds a patient actually absorbed, as in the Hong Kong case. Standard workplace drug screens don't look for any of the three.
Does Drying or Cooking Remove Muscarine?
No. Muscarine is heat-stable, so drying and ordinary cooking don't destroy it. That's different from ibotenic acid, which heat partly converts to muscimol. Processing shifts the balance between fly agaric's main compounds but leaves the muscarine fraction largely where it was.
The royal fly agaric case shows why this matters. In Elonen's 1979 report, two of three patients who ate cooked Amanita regalis had copious salivation or sweating. The authors noted that cooking didn't neutralise the toxins. Our royal fly agaric dosage guide explains why that's one more reason to start low with that species.
Water is a different story. Muscarine dissolves readily, so like the other compounds, it would pass into cooking water. Our decarboxylation guide covers what heat and water do to ibotenic acid and muscimol.
What Does This Mean for People Who Use Fly Agaric?
Mostly, it explains side effects. If you've had sweating, a runny nose, watery eyes or stomach cramps after fly agaric, muscarine is a plausible cause, especially if it varies between batches. It's not a sign that something has gone badly wrong, but it's a reason not to take more.
A few practical points follow:
- Note cholinergic signs in your log. If they appear with one batch and not another, that's useful information.
- Don't push through them. Heavy sweating with a slow pulse or severe cramps needs medical advice.
- Be wary of new species. Muscarine has never been measured in royal fly agaric or the panther cap's market material.
- Mention it if you need help. Telling a clinician "lots of sweating and drooling" changes how they think about the case.
Our side effects and interactions guide sets out the wider picture, and the drug testing article explains how labs measure these compounds.
Frequently Asked Questions
Does Amanita muscaria contain muscarine?
Yes. Muscarine was first isolated from fly agaric in 1869. Older sources put it at a trace 0.0003% of fresh weight, but a 2025 analysis found 0.004–0.043%, well above that consensus. Levels seem to vary widely between samples.
Is muscarine what makes fly agaric psychoactive?
No. The main effects come from ibotenic acid and muscimol, identified in the 1960s. Muscarine acts mostly on the body, not the brain, because it crosses into the brain poorly. It may explain side effects such as sweating and salivation.
What are the symptoms of muscarine?
Sweating, salivation, watery eyes, small pupils, a slow heart, stomach cramps and diarrhoea. In a 2025 survey, 53 people reported such cholinergic symptoms after fly agaric at commonly used amounts of 1–20 g dried.
Does drying Amanita muscaria remove muscarine?
No. Muscarine is heat-stable, so drying and ordinary cooking don't break it down. Drying changes the balance of ibotenic acid and muscimol, but it leaves muscarine largely intact. Like the other compounds, it dissolves in water.
Which mushrooms cause real muscarine poisoning?
Mainly fibrecaps (Inocybe) and some small Clitocybe species, which carry far more muscarine than fly agaric. They cause a classic cholinergic poisoning that doctors treat with atropine. In a 2023 case, muscarine was confirmed in two patients' urine.
Related Articles
- Ibotenic Acid vs Muscimol
- Chemical Composition of Amanita Muscaria
- How Amanita Muscaria's Compounds Affect the Body
- Amanita Muscaria Side Effects and Interactions
- Royal Fly Agaric Dosage Guide
Sources
- Feeney K, Kababick J, Wise S. An examination of cholinergic symptoms produced by the fly agaric mushroom Amanita muscaria (Agaricomycetes): revisiting the role of muscarine. Int J Med Mushrooms. 2025;27(7):1-15. PubMed 40228215
- Rubel W, Arora D. A study of cultural bias in field guide determinations of mushroom edibility using the iconic mushroom, Amanita muscaria, as an example. Economic Botany. 2008;62(3):223-243. doi:10.1007/s12231-008-9040-9
- Chan TYC, Ng SW, Chan CK, Lee HHC, Mak TWL. Cholinergic mushroom poisoning with a detection of muscarine toxin in urine. J Med Cases. 2023;14(6):222-226. PubMed 37435104
- Patocka J, Wu R, Nepovimova E, Valis M, Wu W, Kuca K. Chemistry and toxicology of major bioactive substances in Inocybe mushrooms. Int J Mol Sci. 2021;22(4):2218. PubMed 33672330
- Dörner S, Trottmann F, Jordan PM, et al. The fatal mushroom neurotoxin muscarine is released from a harmless phosphorylated precursor upon cellular injury. Angew Chem Int Ed Engl. 2024;63(52):e202417220. PubMed 39432715
- Łukasik-Głębocka M, Druzdz A, Naskręt M. Clinical symptoms and circumstances of acute poisonings with fly agaric (Amanita muscaria) and panther cap (Amanita pantherina). Przegl Lek. 2011;68(8):449-452. PubMed 22010435
- Ginterová P, Sokolová B, Ondra P, Znaleziona J, Petr J, Ševčík J, Maier V. Determination of mushroom toxins ibotenic acid, muscimol and muscarine by capillary electrophoresis coupled with electrospray tandem mass spectrometry. Talanta. 2014;125:242-247. PubMed 24840440
- Elonen E, Tarssanen L, Härkönen M. Poisoning with brown fly agaric, Amanita regalis. Acta Med Scand. 1979;205(1-2):121-123. PubMed 760400