"All studies included in this review have suggested that psilocybin has a favorable safety profile, being well tolerated in general (see Table 2). The most common adverse events reported were transient hypertension, anxiety and nausea, and headaches that were limited to the experimental sessions in the majority of cases. These events go in accordance with previous reports.13,42,54,55 The occurrence of adverse events was more often reported with higher doses of psilocybin27; however, out of all studies, there were no reports of serious adverse events and all adverse events were readily managed by the staff without the need of pharmacological intervention. The safety of psilocybin use is conditioned mainly by the individual’s expectations and the surrounding environment, which explains the wide amplitude of subjective effects4 and the concern about the conditions under which drug sessions were conducted in many of the studies cited."
Castro Santos, H., & Gama Marques, J. (2021). What is the clinical evidence on psilocybin for the treatment of psychiatric disorders? A systematic review. Porto biomedical journal, 6(1), e128. doi.org/10.1097/j.pbj.0000000000000128