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Acute, subacute and long-term subjective effects of psilocybin in healthy humans: a pooled analysis of experimental studies

Erich Studerus, Michael Kometer, Felix Hasler, Franz X. Vollenweider

Journal of Psychopharmacology September 20, 2010 DOI: 10.1177/0269881110382466 (opens in new tab)

Study at a glance

AI-extracted from the abstract
Characteristics Pooled analysis of double-blind placebo-controlled experimental studies Peer reviewed
Sample size 110
Population Healthy human subjects
Intervention Psilocybin
Dose 45–315 µg/kg body weight
Topics Anxiety Psilocybin
Keywords Dysphoria Hallucinogen Adverse effect Context archaeology Mood Placebo Psychosis Clinical psychology Pharmacology
Citations 529
Key findings Moderate doses of psilocybin in healthy, well-prepared subjects under careful monitoring produce an acceptable level of risk, with acute adverse reactions limited to high doses and manageable without medication.

Abstract

Psilocybin and related hallucinogenic compounds are increasingly used in human research. However, due to limited information about potential subjective side effects, the controlled medical use of these compounds has remained controversial. We therefore analysed acute, short- and long-term subjective effects of psilocybin in healthy humans by pooling raw data from eight double-blind placebo-controlled experimental studies conducted between 1999 and 2008. The analysis included 110 healthy subjects who had received 1–4 oral doses of psilocybin (45–315 µg/kg body weight). Although psilocybin dose-dependently induced profound changes in mood, perception, thought and self-experience, most subjects described the experience as pleasurable, enriching and non-threatening. Acute adverse drug reactions, characterized by strong dysphoria and/or anxiety/panic, occurred only in the two highest dose conditions in a relatively small proportion of subjects. All acute adverse drug reactions were successfully managed by providing interpersonal support and did not need psychopharmacological intervention. Follow-up questionnaires indicated no subsequent drug abuse, persisting perception disorders, prolonged psychosis or other long-term impairment of functioning in any of our subjects. The results suggest that the administration of moderate doses of psilocybin to healthy, high-functioning and well-prepared subjects in the context of a carefully monitored research environment is associated with an acceptable level of risk.

In the evidence

This study is part of the evidence base for a synthesis in the library. Here is how each one recorded it.

  • Moderate psilocybin doses were mostly described as pleasurable and non-threatening, but acute anxiety/panic occurred only at the two highest dose conditions in a small proportion of subjects and was managed with support.

    Synthesized

Comparable studies

Other randomized controlled trials on psilocybin for anxiety, most cited first.

Study Year Design Participants
Psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life-threatening cancer: A randomized double-blind trial Cancer patients with life-threatening diagnoses and symptoms of depression and/or anxiety 2016 Randomized controlled trial n = 51
Rapid and sustained symptom reduction following psilocybin treatment for anxiety and depression in patients with life-threatening cancer: a randomized controlled trial Patients with cancer-related anxiety and depression 2016 Double-blind, placebo-controlled, crossover trial n = 29
Psilocybin can occasion mystical-type experiences having substantial and sustained personal meaning and spiritual significance Hallucinogen-naïve adults reporting regular participation in religious or spiritual... 2006 Double-blind study n = 36
Pilot Study of Psilocybin Treatment for Anxiety in Patients With Advanced-Stage Cancer Adults with advanced-stage cancer and anxiety 2010 Double-blind, placebo-controlled study n = 12
Efficacy and safety of psilocybin-assisted treatment for major depressive disorder: Prospective 12-month follow-up Patients aged 21–75 with moderate to severe unipolar depression 2022 Randomized waiting-list controlled study n = 27

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