Journal of Psychoactive Drugs
November 6, 2024
Rotem Petranker, Valentyn Sobolenko, Zeina Beidas et al.
9 citations
People who exclusively microdose psychedelics differ from those who also take larger doses. Exclusive microdosers are older (average 46.4 vs. 42.0 years), more often female (68.4% vs. 44.7%), non-Caucasian (25.4% vs. 14.7%), and urban residents (43.9% vs. 38.5%). They report using fewer non-psychedelic substances over their lifetime (3.8 vs. 4.7 substances). Most microdose multiple times a month (52.5%), commonly using psilocybin (74.5%), LSD (34.4%), or ketamine (15.8%), and 64.6% do not test their substances. The main reason for microdosing is improving general wellbeing (73.0%).
npj Mental Health Research
November 8, 2023
Omer A. Syed, Benjamin Tsang
4 citations
Microdosing psilocybin, taking roughly a tenth of a full psychedelic dose, is becoming increasingly popular. These sub-perceptual doses cause no psychedelic effects, but anecdotal reports suggest they improve mental wellbeing, boost creativity, attention, and sociability, and treat low mood and anxiety. Recent self-report survey studies demonstrate overwhelmingly positive effects of microdosing on users' mental health.
Neuroscience & Biobehavioral Reviews
May 9, 2025
Rotem Petranker, Benjamin Tsang, Omer A. Syed
3 citations
A narrative review of 12 studies on microdosing LSD, psilocybin, or DMT in rats, mice, and zebrafish found that microdosing caused little change in behaviors related to anxiety- and depressive-like states. The practice was well-tolerated across species, but specific safety concerns remain unaddressed. The authors recommend future research prioritize replication of existing findings, standardize methodologies, explore mescaline microdosing, examine sex-dependent effects, and extend studies to models of obsessive-compulsive disorder and post-traumatic stress disorder.
Psychiatry Research
December 29, 2025
Omer A. Syed, Sean M. Nestor, M.ishrat Husain et al.
1 citation
Adverse event reports for classic psychedelics and MDMA in the WHO global pharmacovigilance database VigiBase show that most reports were for MDMA (1,573) and LSD (394), with fewer for psilocybin (56), DMT (18), and mescaline (15). The most common adverse events were psychiatric, particularly substance abuse and dependence. Overdose reports made up 1.1 to 1.7% of total adverse events. Pregnancy-related and congenital disorders were rare. Compared to acetaminophen, LSD and MDMA were associated with significantly greater odds of reported alcohol abuse, substance use disorder, and substance dependence, and these odds were also greater than those for oxycodone. This exploratory analysis provides a first look at real-world safety data, though findings are limited by potential underreporting and co-use of other substances.
CNS Drugs
July 1, 2026
Omer A. Syed, Valentyn Sobolenko, Sean M. Nestor et al.
Most demographic and clinical variables do not reliably predict who will benefit from ketamine or esketamine for treatment-resistant depression, though a few promising factors—such as early response to treatment and a family history of substance use disorders—warrant further study. This systematic review synthesized 122 studies involving 12,674 participants, finding that the majority of 77 examined predictor variables showed no association with antidepressant outcomes. The review included both unipolar and bipolar treatment-resistant depression, with most studies using intravenous ketamine at a fixed 0.5 mg/kg dose.
Research Square
February 23, 2026
Rotem Petranker, Norman Farb, Omer A. Syed et al.
Repeated low doses of psilocybin were safe and well tolerated in adults with major depressive disorder but did not show greater antidepressant effects than placebo. In a randomized, double-blind trial, 39 participants received either 2 mg psilocybin or placebo weekly for four weeks. Both groups reported similar reductions in depression scores on the PHQ-9 (psilocybin: -5.4; placebo: -6.0) and other measures. The microdose-first group showed slightly more improvement on a dysfunctional attitudes scale than the placebo-first group. No serious adverse events occurred, and symptom reductions continued during an open-label phase. Trial participation itself contributed to clinically meaningful improvement.
Neuroscience & Biobehavioral Reviews
January 24, 2026
Omer A. Syed, Benjamin Tsang, Sean M. Nestor et al.
Psilocybin-assisted therapy (PAT) shows a large and significant antidepressant effect in treating major depressive disorder, based on a meta-analysis of seven randomized controlled trials involving 522 participants. Larger effects were associated with bodyweight-adjusted dosing, longer preparation, dosing, and integration sessions, and non-manualized psychotherapy, though subgroup differences were not statistically significant. The review provides preliminary guidance for clinicians designing PAT protocols.
November 16, 2025
Zeina Beidas, Anya Ragnhildstveit, Adam Blackman et al.
preprint
A phase II trial will test whether microdosing psilocybin (2 mg weekly) outperforms placebo for major depressive disorder. Forty adults will receive either psilocybin or placebo for four weeks, then all will receive psilocybin for another four weeks. Depression symptoms and other measures will be assessed at baseline, after four weeks, and after eight weeks, with follow-ups for two years. The study aims to clarify whether microdosing has genuine antidepressant effects or whether benefits are due to expectancy, and to inform future dose regimens and the therapeutic role of sub-threshold versus threshold doses.