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Are psychedelics dangerous? - What the research says

an illustration saying will they turn you on or will they turn on you


Anne K Schlag, Jacob Aday, Iram Salam, Jo C Neill, David J Nutt


February 3, 2022

Psychedelic medicines are a rapidly developing area of clinical research and public health policy. Despite an increasing body of studies highlighting their efficacy to treat a broad range of medical conditions, psychedelic drugs remain a controversial issue amongst the public and politicians, tainted by previous stigmatisation and perceptions of risk and danger. This narrative review aims to separate the anecdotes and misinformation from the systematic evidence. We cover the classic serotonergic psychedelics (5HT2A receptor agonists): these are plant derived medicines; psilocybin, N,N-dimethyltryptamine (DMT), ayahuasca, mescaline and those synthesised in the laboratory, d-lysergic acid diethylamide (LSD).

We look at the potential adverse effects of these psychedelics, using the current science to outline risks as well as anecdotes surrounding harms. Many of these risk perceptions originate from the first wave of psychedelic research in the middle of last century often in line with sensationalised media reports. Yet these perceptions still contribute to today’s stigmatisation of these substances.

Taking a high-level perspective, we address both psychological and psychiatric risks, such as abuse liability and potential for dependence, as well as medical harms, including toxicity and overdose. We explore the evidence base for these adverse effects to elucidate which of these harms are based largely on anecdotes versus those that stand up to current scientific scrutiny.

Some of the perceived harms of psychedelics, e.g., that they lead to addiction and are neurotoxic, are largely refuted by the research of the past decades. Other risks, such as the risks of psychotic episodes, Hallucinogen Persistent Perception Disorder or overdose are rare, and only reported in individual cases, but these risks still need to be minimised by careful patient selection and preparation. The past decade of research and clinical experience have increasingly demonstrated how psychedelics can be used safely under medical supervision, and safe use guidelines are progressively well defined.

Looking at differences between clinical vs non-clinical uses and users, we stress that whilst these categories are blurred and use and users might be overlapping between categories, notable differences can be discerned in users’ set and setting, as well as the pre- and aftercare experienced- both areas where above adverse effects are potentially exacerbated.

We conclude that medical risks are often minimal, and that many- albeit not all- of the persistent negative perceptions of psychological risks are unsupported by the currently available scientific evidence, and that many of the reported adverse effects are not being observed in a regulated and/or medical context. This highlights the importance for clinicians and therapists to keep to the highest safety and ethical standards.

Still today, psychedelics attract emotive and often polarised opinions. It is essential to address negative perceptions now as psychedelics are increasingly shown to treat a broad range of hard-to-treat disorders, with the potential to treat many more. Similarly, it is imperative not to be overzealous and to refrain from presenting psychedelic medicines as a panacea for all conditions. Balanced media reporting is essential to avoid future controversies, so that much needed research can continue.

Regulatory and legal hurdles of getting psychedelic medicines proven as mainstream medicines are still substantial so overcoming historic misperceptions is vital. The past decade has seen an increasing focus on research on the therapeutic applications of psychedelics- a direct benefit for the public, which is positively represented in current media.  A recent YouGov study (2017) indicates public perceptions in the US becoming more positive, with the majority (63%) being open to medical treatment with psychedelics if faced with a pertinent medical condition, and a UK YouGov survey (2021) corroborates these results

These changes in public interest are in line with the recent regulatory changes in the US and Canada. Collectively, these changes in public perception and regulation suggest that the stigma surrounding psychedelics may be beginning to dissipate, and that society is moving away from previous negative narratives to a more scientific, evidence-based approach to risks and benefits of psychedelics as medicine.

For open-access to the full report of this research, see below:

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