Emerging Psychedelic Mushroom Alternative More Toxic Than Fentanyl, New Research Suggests (2024)

An emerging alternative to psychedelic mushrooms is more dangerous than advertised, public health researchers are warning.

In a new paper, they highlight the toxicity of the Amanita muscaria mushroom, which is increasingly being sold as an unregulated supplement. More has to be done to protect people from the fungi, the authors say, such as the U.S. government classifying it as a controlled substance. The new research was led by scientists from the University of California San Diego Herbert Wertheim School of Public Health and Human Longevity Science.

A. muscaria, also known as “fly agaric,” can be easily identified via its bright colored—usually red—cap covered in white spots (it and similar-looking fungi likely inspired the mushroom item now common in Mario games). It’s known to have hallucinogenic properties and was once used during rituals by some societies in parts of the Old World. But the mushroom’s use as a drug was largely supplanted by the discovery of psilocybin-containing mushrooms in the Americas.

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In recent years, scientists have explored psilocybin’s potential to treat depression and other mental health disorders, sparking increased public interest in magic mushrooms. The authors of a new paper, published in June in the American Journal of Preventive Medicine, note that this popularity has also revived the use of A. muscaria. But unfortunately for potential consumers, the two fungi have some very important differences.

Both mushrooms can cause some similar symptoms, such as visual hallucinations. But the researchers note that the primary ingredients in A. muscaria—muscimol and ibotenic acid—are not classic psychedelics like psilocybin and are riskier to consume. They point to mice studies suggesting that both compounds have a higher toxicity (measured as how much of a dose it would take to kill 50% of users) than most commonly used psychotropic drugs, including fentanyl, PCP, and cocaine. They also cite several recent case reports of people being hospitalized or even dying from taking A. muscaria. While psilocybin mushrooms are not free of potential side effects either, they’re thought to have low toxicity and a very rare risk of fatal overdose.

Adding to the potential danger of A. muscaria is the lack of regulation surrounding its use, the authors say. Neither the mushroom nor its compounds are included in the federal government’s Controlled Substances list (the state of Louisiana does have its own version that includes it). So there are no rules right now that govern how it can be grown or used. Some companies are also selling the mushrooms as dietary supplements, which almost certainly isn’t legal even under the very loose regulations of the industry. And these supplements are often intentionally fostering confusion between the different kinds of mushrooms.

“There is a lot of interest in the therapeutic potential for psilocybin and for good reason. But at the same time, a growing industry may be trying to capitalize on this interest by marketing other mushrooms,” said senior study author Eric Leas in a statement from the university. “For example, some manufacturers are calling Amanita muscaria products ‘magic mushroom gummies’ and not disclosing what mushroom they contain, or not making it clear Amanita muscaria is a different mushroom than psilocybin and has essentially no clinical evidence supporting its use as a therapy.”

More needs to be done to rein in the sale of these products and to inform potential users of the drug’s risk, Leas and his team say. They offer a spectrum of solutions, from listing it as a controlled substance to mandating age restrictions or childproof packaging for supplements containing it.

“Given the substantial risks associated with the consumption of Amanita muscaria products, it is a ‘buyer beware’ marketplace where consumers are at risk and manufacturers are profiting from delayed regulatory enforcement,” the authors wrote. “The time for a public health first response is now.”