Reporting of side-effects in clinical trials of psilocybin-assisted psychotherapy for psychiatric conditions: systematic review

BACKGROUND: Psilocybin-assisted psychotherapy (PAP) has gained attention as a promising intervention for conditions including depression, anxiety and post-traumatic stress disorder, but understanding of its side-effects is limited. This review evaluates the quality of side-effects reporting in PAP trials, to guide treatment, policy and research. AIMS: To assess side-effects reporting quality in PAP trials for psychiatric conditions, comparing published articles and ClinicalTrials.gov records. METHOD: A PROSPERO-registered review (no. CRD42023458960) included English-language PAP trials (2005-2024) identified via Embase, CENTRAL, PubMed and reference searches. Reporting quality was assessed using the CONSORT Harms extension, categorised as either high (17-21), moderate (12-16), low (7-11) or very low (0-6). Randomised controlled trials underwent risk of bias analysis, and descriptive statistics compared side-effects across sources. RESULTS: = 9) showed high risk of bias for side-effects outcomes. Variability in reporting hindered comparisons between articles and ClinicalTrials.gov, underscoring the need for standardisation. Overall, there was no evidence of systematic underreporting of side-effects in published articles compared with trial registers. CONCLUSIONS: Side-effects reporting in PAP trials is inconsistent but is improving over time. Existing evidence has a high risk of bias. Future trials should align with best-practice guidelines for side-effects reporting. Discussions with patients should prioritise findings from high-quality studies and emphasise the current uncertainty regarding PAP side-effects.