Microdosing psychedelics: Current evidence from controlled studies

Taking regular low doses of psychedelic drugs (microdosing) is a practice that has drawn recent scientific and media attention for its potential psychotherapeutic effects. Yet, controlled studies evaluating this practice have lagged. Here we review recent evidence focusing on studies that were conducted with rigorous experimental control. Studies conducted under laboratory settings using double-blind placebo-controlled procedures and investigator-supplied drug were compiled. The review includes demographic characteristics of the participants and dependent measures include physiological, behavioural, and subjective effects of the drug(s). Fourteen studies met the review criteria, all of which involved acute or repeated low (5-20 μg) doses of lysergic acid diethylamide (LSD). Acute microdoses of LSD dose-dependently altered blood pressure, sleep, neural connectivity, social cognition, mood, and the perception of pain and time. Perceptible drug effects were reported at 10-20 μg but not 5 μg. No serious adverse effects were reported. Repeated doses of LSD did not alter mood or cognition on any of the measures studied. The findings suggest that low doses of LSD are safe and produce acute behavioural and neural effects in healthy adults. Further studies are warranted to extend these findings to patient samples and to other psychedelic drugs, and to investigate microdosing as a potential pharmacological treatment for psychiatric disorders.