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About this resource
This is an English version of a 2024 paper that systematically collected acute adverse events involving psilocybin used in therapeutic research from double-blind randomized clinical trials. Six trials with 528 participants were analyzed, principally comparing headache, nausea, anxiety, dizziness, increased blood pressure, and other events occurring within 48 hours after administration with comparison groups.
The review does not answer every question contained in “Is psilocybin safe?” across all periods and populations. Included trials selected participants, used clinical monitoring, and took place in settings that included psychological support. Rare serious events, long-term mental states, repeated exposure, and mushroom products in general environments were outside its scope or had insufficient evidence.
Study design
The authors searched for double-blind randomized trials evaluating psilocybin against placebo or a comparison intervention under research conditions intended for therapeutic use. They extracted adverse-event counts from adult trials addressing depression, anxiety, and other conditions and pooled relative differences in occurrence by event. The acute period was generally defined as through 48 hours after administration.
Adverse-event reporting was not necessarily standardized across trials. Questions asked of participants, severity categories, collection time points, and comparison groups differed, so an absence of reporting cannot be equated with an absence of events. Psilocybin’s strong subjective effects also leave uncertainty about whether blinding was maintained in practice.
The research mainly involved selected adults with a mean age of approximately 40 years, and trials often excluded people at risk for psychotic disorders or mania and those with serious physical illness. This may represent a population managed more safely than the general population.
Content
Safety assessment needs to distinguish expected transient reactions from serious or persistent adverse events. Even a temporary headache or nausea may be distressing and may contribute to dehydration, falls, panic, or worsening of an existing condition in some circumstances. Conversely, observing an acute rise in blood pressure does not by itself prove long-term cardiovascular injury.
Psilocybin research emphasizes “set and setting” and psychological support. Scientifically, this means preparation, monitoring, interpersonal support, and emergency response are part of the trial intervention, so the same outcomes and safety cannot be expected when the substance is separated from them. Participants were observed continuously during sessions and received support when needed.
Comparison groups can also experience headache, anxiety, or nausea. By considering differences from comparison groups rather than raw event counts alone, the review assessed signals associated with psilocybin exposure.
Results
Pooled findings indicated that acute events such as headache, nausea, anxiety, dizziness, and increased blood pressure tended to occur more often in psilocybin groups than in comparison groups. Most were reported to resolve within 48 hours. Within the included trials, serious events requiring medical intervention for acute adverse effects were not common.
The average statement that “most resolved” does not mean every participant had mild symptoms. Definitions and cases in individual trials need to be examined. Acute anxiety may encompass fear, confusion, panic-like reactions, and different experiences. The meaning of elevated blood pressure likewise varies with underlying disease and measured values.
The review captures acute events relatively well but is not large enough to exclude delayed symptoms or events occurring in 1 among several thousand people. A total of 528 participants is useful for clinical research but small for determining rare public-health risks.
Limitations
Only 6 trials could be included, and target conditions, comparison groups, psychological support, and adverse-event collection methods differed. Results from selected participants at experienced research facilities cannot be generalized to unsupervised settings or mushrooms of unknown identity. Trials used standardized psilocybin and did not evaluate variation in amounts or other constituents in mushrooms.
Because follow-up centered on the first 48 hours, it could not adequately address long-term or rare outcomes such as persistent perceptual changes, mania, psychotic symptoms, suicide-related events, dependence, or repeated use. Exclusion criteria removing higher-risk people are another important constraint when transferring safety findings to the general population.
Unblinding may influence adverse-event reports and expectations. Pharmaceutical and research funding, preregistration, and the existence of unpublished data also matter when evaluating the review’s completeness.
Safety
Anxiety, confusion, headache, nausea, dizziness, and changes in blood pressure and heart rate may occur acutely. Personal or family history of psychotic or bipolar disorders, cardiovascular disease, pregnancy, and medication interactions are often subjects of exclusion or evaluation in controlled research. An individual’s safety cannot be judged from averages alone.
This page does not guide amounts, preparation, combinations, or self-treatment. Mushrooms containing psilocybin add separate risks of species misidentification, variable constituent content, and confusion with other poisonous mushrooms; trials of standardized preparations cannot guarantee their safety.
Nor does this evidence support independently changing or discontinuing treatment for depression or anxiety. Acute severe confusion, chest pain, impaired consciousness, or risk of harm to self or others calls for ordinary emergency response rather than continued review of research information.
The severity and frequency of adverse events also need to be considered separately. Common mild symptoms and rare but serious symptoms require different forms of assessment. Few serious cases in short-term trials do not mean the probability is zero.
Source and rights
Original source: Yerubandi N, et al. Acute Adverse Effects of Therapeutic Doses of Psilocybin: A Systematic Review and Meta-Analysis. JAMA Network Open. 2024;7(4):e245960. DOI: 10.1001/jamanetworkopen.2024.5960.
The original article is available under Creative Commons Attribution 4.0 (CC BY 4.0). This page is a source-aligned English translation under that license, reconstructed while preserving the argument and principal categories. It is not literal, and explanatory context has been added to avoid conflating acute and long-term safety. Figures and tables are not reproduced. The original source takes precedence for exact event counts, effect estimates, confidence intervals, and trial-level assessments.