Psilocybin microdosing in the United States: Insights from a nationally representative survey

Abstract Background and Aims There has been a resurgence of interest in using psilocybin to treat various mental health conditions. Although some adults in the United States (US) are using psilocybin, little is known about the epidemiology of its use, especially for microdosing (i.e., taking a fraction of a regular dose). This study aimed to present nationally representative survey results about people who microdose psilocybin in the US. Methods A probability‐based and nationally representative survey of individuals living in the US was fielded from December 2023 to January 2024. A population estimate of how many US adults have microdosed, recency of microdosing, and intentions for microdosing was calculated using sample weights designed to produce national estimates. Multinomial logit models were used to identify predictors of microdosing status across demographic characteristics. Results Of 4253 respondents who completed the screener, 554 reported using psilocybin in their lifetime. Among the 12.1% of US adults who used psilocybin in their lifetime, 26.5% (95% Confidence Interval CI: 21.5–32.1%) reported they microdosed the last time they used, 57.5% (95% CI: 51.5–63.2) reported they did not microdose, and 14.6% (95% CI: 10.8–19.5) did not know or were unsure. Among the 3.1% of adults who used psilocybin in the past year, 46.9% (95% CI: 35.3–58.8) reported they microdosed the last time they used, 45.6% (95% CI: 34.2–57.5) reported they did not microdose, and 6.1% (95% CI: 2.8–12.8) did not know or were unsure. Compared with those who did not microdose the last time they used psilocybin, those who did were 12 percentage points (p = 0.002) more likely to have used psilocybin for improved physical health and 25 percentage points (p < 0.001) more likely to have used for improved mental health (including to address substance use disorders). Those who microdosed were also 27 percentage points (p < 0.001) less likely to report using psilocybin for fun or pleasure than those who did not microdose at last use. Individuals who used psilocybin more recently (in the past year) were 25 percentage points (standard error: 0.07; p < 0.001) more likely to report microdosing than those who used more than a year ago. Conclusions At least 8.4 million US adults have microdosed psilocybin in their lifetime. Those who have used psilocybin within the past year are more likely to report microdosing the last time they used than those who have used psilocybin more than one year ago; however, approximately 15% respondents who used psilocybin in their lifetime were unsure whether they microdosed the last time they used. Improving physical and mental health are the top motivations for self‐reported microdosing among US adults.