Anxiety, nausea and headaches common side effects
The study found that most drugs caused anxiety, nausea and headaches in a significant percentage of patients. For the most part, these disappeared over time. Importantly, anxiety was often considered a side effect; whereas anxiety includes a wide range of psychologically challenging events that may also be beneficial to the therapeutic process. Separating truly harmful events from potentially beneficial effects is complex, but crucial to improving the understanding of psychedelic treatments.
Serious side effects appear to be largely absent based on the included studies, as do lasting physiological side effects. Suicidal ideation and suicidal behaviour were rare but did occur. These represent serious psychiatric emergencies, which emphasizes the importance of investigating which patients are most at risk and how best to reduce the risk of side effects.
An important limitation is that, in many studies adverse effects were not systematically assessed, probably underreported and poorly defined in the context of psychedelic treatments.
Side effects inadequately evaluated
This study included 44 articles (34 quantitative and 10 qualitative) that described treatments with MDMA and serotonergic psychedelics (psilocybin, lysergic acid diethylamide (LSD) and ayahuasca) in 598 unique patients. In general, side effects were inconsistently defined and inadequately evaluated.
Future studies should more comprehensively describe the timing and severity of the effects, e.g., using scales such as the Challenging Experiences Questionnaire (CEQ). Many studies included patients with previous psychedelic experience, which may bias results and limit generalizability. Future studies should employ qualitative methods, which can add nuance by elaborating and understanding the meaning of challenging experiences, thereby refining our understanding of adversity.
Full transparency about adverse events is a responsibility of clinicians, especially in a burgeoning field fueled by the enthusiasm of pioneering researchers. Understanding the full spectrum of unpleasant, potentially harmful, and transformative treatment-related events is critical to informing future therapists who may otherwise not be optimally prepared to handle challenging and potentially destabilizing patient experiences, particularly in larger groups of patients with more complex and potentially comorbid conditions.
The results of the study were published in the Journal of Psychopharmacology on the 26th of august: https://doi.org/10.1177/02698811221116926