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Toxicology Rounds

Toxicology Rounds

Coming to an ED Near You: Magic Mushrooms and Psychedelic Cacti

Gussow, Leon MD

doi: 10.1097/01.EEM.0000737488.51174.02
    psychedelics, mushrooms

    Few emergency physicians have firsthand experience managing exposures to psilocybin or peyote, but encounters with patients who have ingested these hallucinogenic plants will inevitably increase in the coming years because of recent political and legal developments.

    Denver, CO, decriminalized the growth, possession, and use of psilocybin mushrooms in 2019. That same year, Oakland, CA, decriminalized possession of a number of psychedelic drugs and plants including psilocybin, peyote, ayahuasca, and ibogaine.

    The trend continued in 2020. Oregon voters passed a measure allowing for psilocybin to be used in regulated and licensed psychotherapeutic facilities. That state's voters also approved a separate measure decriminalizing possession of limited amounts of psychedelic mushrooms containing psilocybin. Santa Cruz, CA, and Ann Arbor, MI, also decriminalized use and possession of peyote and psilocybin, as did Washington, D.C., where voters passed the Entheogenic Plants and Fungus Policy Act of 2020.

    Decriminalization, of course, is not the same as legalization. Psilocybin and peyote are still classified as Schedule I drugs, and are illegal under federal law. None of the measures allows for commercial growth or sale of psychedelic drugs in the way Cannabis is legal in many states. Decriminalization simply means that local police will not prioritize enforcing laws prohibiting use and possession of small amounts of these drugs.

    Still, the growing movement to loosen regulations on psilocybin and peyote means that the availability of these drugs will become more common, and emergency departments will inevitably see more patients exposed to them.


    Most hallucinogenic drugs are either tryptamines or phenethylamines. Psilocybin is a tryptamine, which means that its structure is similar to that of the essential amino acid tryptophan, with abutting 5-carbon and 6-carbon rings. Endogenous tryptamines include serotonin and melatonin. DMT, another tryptamine, is the active psychotropic component of the brew used in ayahuasca ceremonies.

    Psilocybin is found in a number of fungi. These are the so-called magic mushrooms such as Psilocybe cyanescens, P. cubensis, and P. mexicana. These species grow predominantly in Florida, California, and the Pacific Northwest. They are also commonly cultivated indoors. One striking characteristic of many psilocybes is that they develop a bluish discoloration when the stems are bruised.

    Psilocybin is usually ingested as a dried mushroom preparation or a tea. Once ingested, psilocybin—an inactive prodrug—is rapidly converted to the active metabolite psilocin by enzymes in the GI tract. The hallucinogenic dose is often said to be two to six mushrooms, but this can vary with the potency of the sample.

    Psilocin is an agonist at the serotonin 5-HT2A receptor, so it acts as a sympathomimetic hallucinogen. Signs and symptoms of exposure include tachycardia, hypertension, nausea and vomiting, agitation, panic attacks, and paranoia. Hallucinations can be auditory or visual. The user can also experience distortions in the perception of space and time.

    Effects usually begin within 20 minutes of ingestion and last four to six hours. Psilocybin rarely produces severe toxicity when taken alone, but the resulting disorientation, confusion, and agitation can lead to self-induced trauma from, say, jumping out of a tree or walking into traffic.

    No specific antidote is available. Medical management is supportive care, providing a calm environment, and sedation with benzodiazepines as needed.


    The crown of the spineless peyote cactus, Lophophora williamsii, contains mescaline, a phenethylamine derived from the amino acid phenylalanine. The peyote cactus grows in the southwestern United States and northern Mexico. Peyote has been used for millennia to facilitate religious and spiritual ceremonies by the Aztecs and other Native Americans.

    Mescaline-containing tops of the peyote cactus are harvested as buttons, and are ingested or consumed as a tea. The usual hallucinogenic dose is six to 12 buttons. Mescaline is an agonist at the 5-HT2A and 5-HT2C receptors, and like psilocin, it acts as a sympathomimetic hallucinogen.

    The taste of peyote is extremely bitter, which may explain the nausea and vomiting experienced by many users before the onset of hallucinogenic effects. A 12-year review of single-substance human exposures to mescaline or peyote reported to the California Poison Control System found only one of 31 patients had documented vomiting. (Clin Toxicol [Phila]. 2010;48[4]:350.) The reason for this discrepancy is not clear. It could be that initial vomiting represents self-decontamination, decreasing the dose absorbed and minimizing symptoms that could cause the user to need medical attention.

    Other manifestations more commonly reported in the study were hallucinations, tachycardia to 190 bpm, agitation, hallucinations, and mydriasis. One patient was intubated (apparently for airway protection) and admitted to the intensive care unit. Rare adverse effects reported in isolated case reports include Mallory-Weiss tears of the esophagus from persistent vomiting and botulism from improperly prepared and stored peyote buttons. Hallucinations and changes in visual perception after ingesting peyote generally start within one to three hours and last for up to 12 hours or more.

    As with psilocybin, managing these patients is focused on supportive care and sedation as needed. Severe or life-threatening effects rarely occur.

    Unusual cases with more serious outcomes do occur. A patient ended up in the ICU after intravenously injecting psilocybin. (J Acad Consultation-Liaison Psych. 11 Jan 2021 [Epub ahead of print]; He developed liver and kidney failure, and required hemodialysis, artificial ventilation, and treatment for fungal sepsis. Just when you think you've seen it all, toxicology has more surprises.

    Dr. Gussowis a voluntary attending physician at the John H. Stroger Hospital of Cook County in Chicago, an assistant professor of emergency medicine at Rush Medical College, a consultant to the Illinois Poison Center, and a lecturer in emergency medicine at the University of Illinois Medical Center in Chicago. Follow him on Twitter@poisonreview, and read his past columns at

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