Side Effects of Microdosing Lysergic Acid Diethylamide and Psilocybin: A Systematic Review of Potential Physiological and Psychiatric Outcomes

Objective Psychedelics are gaining renewed attention, especially through the practice of microdosing, where low doses are taken regularly. Microdosing lysergic acid diethylamide (LSD) and psilocybin is used by both healthy individuals and those with mental health conditions to improve daily functioning, reduce anxiety, and enhance mood and cognition. However, there is limited information about the side effects of this practice. This review aimed to collect and characterize the side effects of psychedelic microdosing.Methods We conducted a systematic review of original papers from PubMed, Web of Science, and Scopus (accessed August 03, 2024) that reported side effects of microdosing LSD and psilocybin. Non-English papers, non-original studies, studies without typical microdosing doses, or those lacking descriptions of side effects were excluded. Our methodology has been developed in accordance with PRISMA guidelines. Because side effects were assessed heterogeneously in these papers, we did not perform a bias evaluation.Results We included 31 studies, 15 of which we classified as laboratory studies with higher quality evidence, and 14 studies with lower quality evidence, as well as 2 clinical cases. Side effects were typically dose-dependent, mild, and short-lived. Common adverse effects included increased blood pressure, anxiety, and cognitive impairment.Discussion This review is limited by the heterogeneity in reporting side effects and the short duration of many studies. Future studies should transparently and systematically present a description of side effects.