—“One side will make you grow taller, and the other side will make you grow shorter.”
—“One side of what? The other side of what?” thought Alice to herself.
—“Of the mushroom,” said the Caterpillar, just as if she had asked it aloud; and in another moment it was out of sight.
– Alice’s Adventures in Wonderland – Chapter V: Advice from a Caterpillar, by Lewis Carroll (1865).

In January of this year, Oregon became the first state in the US to legalize the adult use of hallucinogenic, “psilocybin” containing mushrooms. Psilocybin is a chemical found in certain naturally occurring mushrooms, commonly known as “magic mushrooms”, or more colloquially as “shrooms”.  For historical reference, these are not the same type of mushroom depicted in Lewis Carroll’s 1865, “Alice’s Adventures in Wonderland“.

Oregon’s “Measure 109” authorizes the creation of psilocybin service centers where anyone over 21-years of age can consume psilocybin mushrooms in a supervised setting. Unlike cannabis, which can be sold at dispensaries, Oregon will (supposedly) not allow the retail sale of psilocybin. Rather, the centers provide a location where a state-certified facilitator is present during the drug’s use.

However, after reading carefully, the law also requires the state to issue licenses for the cultivation or processing of psilocybin products, and for laboratories to test them. So I’m not entirely clear on the new law’s commercial distribution aspects, which include more than 90-pages of regulations.

In contrast to Oregon, the United States Drug Enforcement Administration (DEA) classifies psilocybin as a “Schedule I” drug, meaning that it is considered to have a high abuse potential while serving no legitimate medical purpose. Consequently, psilocybin is currently illegal according to Federal regulations.  However, enforcement has been directed more at academic and medical research than public use.

There are around 200 varieties of psilocybin containing mushrooms which grow naturally throughout the Americas.  Most are small, usually brown, and have a bitter taste. In the wild, they can be mistaken for, or with various poisonous mushroom varieties.

The mushrooms are usually prepared for consumption in a way that hides their unpleasant taste. Chocolate brownies are a popular treatment, or they may be brewed into a tea. Dried mushrooms can also be crushed into a powder and packed into capsules.

Accidental poisonings can occur due to eating poisonous mushrooms by mistake. While most such accidental mushroom ingestions result in only minor gastrointestinal illness, the consumption of poisonous mushrooms justifies immediate medical attention. Ground or processed mushrooms may also have been unknowingly mixed with other drugs that can result in unexpected or undesirable effects. And of course, children should never be allowed access to any recreational drugs.

There are no physical symptoms from discontinuing psilocybin use. However, long term use may result in a period of psychological readjustment.  Regular use can also cause psilocybin tolerance, with some crossover tolerance to other similar-acting hallucinogens such as LSD and mescaline.  Long-term personality changes can be observed in many individuals, especially those who engage in frequent use.

“Well, now that we have seen each other,” said the Unicorn, “if you’ll believe in me, I’ll believe in you. Is that a bargain?”
– Through the Looking-Glass, and What Alice Found There, Chapter Seven – The Lion and the Unicorn, by Lewis Carroll (1871).

While there isn’t an established “LD50” (Lethal Dose for 50% of a population) for psilocybin, research on laboratory animals suggest that it would likely well exceed any amount of mushrooms that a human could reasonably consume. I have been able to find references to only two presumably confirmed, and one possible case of deaths associated with psilocybin toxicity; and I can’t locate primary sources for any of them.

A 2015 National Survey on Drug Use and Health (per Johnson, Griffiths, et. al., 2018) in the United States indicated that around one-in-twelve individuals reported having used psilocybin at least once. In the Americas, ritual and spiritual psilocybin use can be traced back to pre-Columbian, Mesoamerican societies.

Psilocybin works by activating receptors for the neurotransmitter, “serotonin” (5-HT2A receptor agonist), primarily in the brain’s “pre-frontal cortex”. This part of the brain is associated with cognition, personality, mood, and the interpretation of perceptions. It can, however, work in other areas of the brain that regulate arousal and panic responses.

Hallucinogenic effects from psilocybin usually occur within 30 minutes, and ordinarily last for 4 to 6 hours. In some cases, and especially with very large doses, changes in sensory perception and thought patterns may persist for up to several days.

The drug can elicit feelings of euphoria, and alter sensory perceptions in ways similar to certain other hallucinogenic drugs, such as LSD. Some individuals experience feelings of peacefulness, and sometimes a sense of clarity, awareness, connection, or “awakening”.

Smaller amounts of psilocybin don’t necessarily cause active visual or auditory hallucinations. Instead, the drug may merely alter the ways in which perceptions are interpreted. Accordingly, the quantity of the drug in a person’s system as well as previous experiences and expectations can strongly affect individual responses.

Modest doses of psilocybin can elicit the streaking of light sources, halos of light, vivid colors, or patterns. Larger doses may also bring about visual and auditory hallucinations, synesthesia experiences, and strong emotional associations.  Effects usually associated with very large amounts of the drug, often referred to as a “heroic dose”, may include a sense of personal dissociation, a feeling that the world is not “real”, disengagement, distorted thought processes, and powerful emotional experiences.

More intense experiences may arrive in waves, with varying degrees of lucidity during intervening moments. Some users may also experience periods of anxiety, panic attacks, or disturbing hallucinations. In a few individuals, the drug may trigger psychotic episodes, especially among people with a family history of psychosis or schizophrenia.

In medical settings, doctors have tested psilocybin for treating cluster headaches, depression, end stage cancer anxiety, post-traumatic stress disorder, and other forms of psychological distress. Some research indicates that psilocybin may assist medical professionals in treatments for depression by reducing symptoms without dulling emotions. Results from studies appear to vary, and not all scientific studies are rigorous, leading some researchers to question the drug’s safety and effectiveness as a therapeutic.

Outward physical indicators of psilocybin in humans can range from dilated pupils or dizziness, to loss of coordination, and nausea and vomiting.  With small or modest doses, an individual may be able to communicate clearly and exhibit few outward indicators of the drug’s effects.

Aside from the physical risks of injury due to impaired coordination or perceptual distortions during unsupervised use, psilocybin also has a potential for undesirable psychological effects, or a “bad trip”. This can range from a sense of fear, agitation or confusion, to delirium, psychosis, and in severe cases, syndromes that resemble schizophrenia. Usually, symptoms resolve as the effects of the drug wear off.

Some individuals, however, can experience persistent, sometimes distressing alterations to the way they see the world. A medical condition known as hallucinogen-persisting perception disorder can include invasive, recurring “flashbacks” of visual images. Psilocybin can also encourage the development of psychiatric disorders in higher-risk populations.

As a personal note, this article is for information ONLY, and neither advocates nor encourages the use of any hallucinogens.  And while I take a personally fairly libertarian perspective toward individual choices made by informed and sober adults, I feel like Oregon’s legalization of psilocybin mushrooms could encourage an overly complacent attitude regarding their use.  During my youth, I watched as a very close friend with a family history of the condition descended into clinical schizophrenia, probably hastened by hallucinogen use.  So I strongly encourage anyone considering such an experience to be fully informed of the risks.

References:

Oregon Measure 109:
https://ballotpedia.org/Oregon_Measure_109,_Psilocybin_Mushroom_Services_Program_Initiative_(2020)

Oregon Psilocybin Service:
https://www.oregon.gov/oha/PH/PREVENTIONWELLNESS/Pages/Oregon-Psilocybin-Services.aspx

DEA Psilocybin Factsheet (pdf): https://www.dea.gov/sites/default/files/2020-06/Psilocybin-2020.pdf

(Meta-study correlating psilocybin dosages to reported experiences.  Table on page 6.)
Hirschfeld, T., & Schmidt, T. T. (2021). Dose–response relationships of psilocybin-induced subjective experiences in humans. Journal of Psychopharmacology, 35(4), 384–397. https://doi.org/10.1177/0269881121992676

(A quite comprehensive, 166 page academic meta-study on psilocybin risks.)
Johnson, M. W., Griffiths, R. R., Hendricks, P. S., & Henningfield, J. E. (2018). The abuse potential of medical psilocybin according to the 8 factors of the Controlled Substances Act. Neuropharmacology, 142, 143–166. https://doi.org/10.1016/j.neuropharm.2018.05.012

(Recent study regarding the effectiveness of psilocybin in assisting treatment for severe depression.)
Gukasyan, N., Davis, A. K., Barrett, F. S., Cosimano, M. P., Sepeda, N. D., Johnson, M. W., & Griffiths, R. R. (2022). Efficacy and safety of psilocybin-assisted treatment for major depressive disorder: Prospective 12-month follow-up. Journal of Psychopharmacology, 36(2), 151–158. https://doi.org/10.1177/02698811211073759

(Pre-print study suggesting that psilocybin works by desynchronizing networks in the brain.)
https://www.medrxiv.org/content/10.1101/2023.08.22.23294131v1

Deaths Attributed to Psilocybin Use (Note: I can find no references to deaths due to psilocybin ingestion in any medical journals.  These are deaths commonly cited by third-parties on the Internet.  However, I haven’t been able to verify any primary sources for the information.) :

Incident: Anonymous Female, 2012
In 2012, a 24-year-old female died due to cardiac arrest 2-3 hours after consuming magic mushrooms. She had received a heart transplant 10 years prior. Six months before her death she had had a clinic review and was “well with no physical limitations”. Autopsy results suggested a high dose of psilocybin-containing mushrooms.

Autopsy confirmed a healthy cardiac allograft (no allograft vasculopathy). Plasma toxicology revealed a psilocin level of 30 mg/L (consistent with magic mushroom toxicity) and a tetrahydrocannabinol level of 4 mg/L. No alcohol or other common drugs of abuse were detected. […] Only two deaths have been previously reported directly attributable to magic mushroom ingestion … We postulate that in this case excessive sympathetic stimulation of the transplanted heart as a result of Psilocybe mushroom toxicity led to fatal ventricular arrythmias.”

Lim TH, Wasywich CA, Roygrok PN. “Letter to the Editor: A fatal case of ‘magic mushroom’ ingestion in a heart transplant recipient”. Internal Medicine Journal. Nov 19, 2012 (online).1268-9.

Incident: Anonymous Female, 1996
One death (commented on by Lim, Wasywich, and Roygrok) was reportedly the result of “neurological sequelae (somnolence and convulsions) 6-8 h after ingestion of an unknown quantity of magic-mushrooms”. Post-mortem toxicology revealed very high plasma psilocin concentration (4000 mg/L).

Gerault A, Picart D. “Intoxication mortelle à la suite de la consommation volontaire et en groupe de champignons hallucinogeèes”. Bull Soc Mycol France 1996;112: 1-14.

Incident: Anonymous, Date Unknown
An early death (commented on by Lim, Wasywich, and Roygrok) of which “details […] are scanty”.
Buck RW. “Mushroom poisoning since 1924 in United States”. Mycologia 1961;53:537-8.