Microdosing meta-analysis finds no clear benefit over placebo in healthy adults

What the meta-analysis found

Meshkat and colleagues searched to February 2026 for studies of repeated sub-hallucinogenic psychedelic doses in healthy adults. They included 24 studies with 3,681 participants; 6 contributed to meta-analyses.¹ The randomized pool was small: two parallel trials, three comparisons, 117 people.

Every interval crosses zero, so none of the differences is statistically significant. Adverse event risks were similar between microdosing and control (two trials, 109 people). Observational studies reported improvements, which the authors say were "likely influenced by expectancy or lifestyle factors", and exploratory pooling across all designs suggested decreases in depressive symptoms and stress. Their conclusion: microdosing "does not show consistent immediate benefits" for these symptoms in healthy adults.¹

An umbrella review points the same way

Özaydın and Canlan Özaydın reviewed three meta-analyses drawing on 14 studies (13 unique samples, 1,614 people). "The sole significant pooled effect was a small decrease in cognitive control" (d = -0.34; 95% CI -0.62 to -0.06), and self-reported mood benefits "are largely attenuated under placebo-controlled conditions".²

Why blinding is the hard part

Microdosing trials struggle to keep people from guessing what they took. In a self-blinding study with 191 completers, both the microdose and placebo groups improved, with no significant difference between them, and small acute differences could be explained by participants breaking blind.³ In a double-blind psilocybin mushroom trial, participants identified their condition in 49 of 64 measurement weeks, and acute effects were stronger on active weeks only among those who guessed correctly.⁴ Reviewers still disagree: a 2024 rapid review concluded that "it is not yet possible to determine whether microdosing is a placebo".⁵

How common microdosing is

RAND's 2025 national survey (10,122 adults, fielded September 9 to October 1, 2025, published January 21, 2026) estimated that 4.26% of US adults, about 11 million people, used psilocybin in the past year. Of past-year users, 69% (95% CI 60.4% to 76.7%; unweighted n = 372) had microdosed at least once.⁶

Why it matters for microdosing claims

The pooled trials were small and enrolled healthy adults, so they can't settle claims about people with depression. For healthy adults, though, claims of mood or stress benefits now sit against a 2026 meta-analysis that found no benefit beyond placebo and a 2026 umbrella review that found mood benefits largely fade under placebo control. Our microdosing research guide walks through each placebo-controlled study.

There's also a measurement problem. In the mushroom trial above, the researchers estimated the psilocybin in each portion from a lab assay and noted it "could have been higher or lower depending on the source".⁴ Psilocybin content differs from one mushroom sample to the next (our potency data collects the published measurements), so the same weight of mushroom doesn't carry a fixed amount of psilocybin.