Microdosing psychedelics: Demographics, practices, and psychiatric comorbidities.

Microdosing is defined as taking sub-perceptual, sub-hallucinogenic amounts of classic psychedelics such as LSD or psilocybin, typically around one-tenth of a full psychoactive dose. Previous literature has established that classic psychedelics act primarily at 5-HT2A receptors and that high-dose psychedelic-assisted therapy has shown promise in several clinical contexts. Popular media and anecdotal reports have attributed a range of benefits to microdosing—improved mood, cognition, creativity, and relief of certain medical symptoms—but academic characterisation of who microdoses and how they do so remains limited. Rosenbaum and colleagues set out to describe the demographics, practices, and basic psychiatric descriptors of a large sample of English-speaking adults who microdose. The primary aim was to document substances, dosages, dosing schedules, psychiatric diagnoses, prescription medication use, and recreational substance use patterns among people who report microdosing, providing an empirical foundation to guide future experimental and clinical research on microdosing psychedelics.

The study used an anonymous, cross-sectional online survey distributed via social media and multiple Reddit subforums related to psychedelics, microdosing, and nootropics. Recruitment language invited both people who had microdosed and those who had not, and there were no exclusion criteria or financial incentives. Ethical approval was obtained from the University of Toronto Social Sciences, Humanities, and Education Research Ethics Board. Between September and November 2017, 1390 people began the survey; after dropouts and exclusions for withdrawal and careless responding the final analytic sample comprised 909 respondents. Questionnaires covered demographics, microdosing regimen (substance, estimated dose, dosing schedule), substance use history (recreational substances and prescription medications), lifetime psychiatric diagnoses (selected DSM-style categories), dispositional personality measures, and a creativity task. Flow through the survey differed by experience: respondents who never microdosed were not shown microdosing-specific items. Missing data were handled by available-case analysis. Analyses were primarily exploratory. Differences in age were tested with Wilcoxon signed-rank tests because age was non-normally distributed. Categorical demographic variables were examined with chi-squared tests followed by odds-ratio testing to characterise specific differences between grouped microdosers and non-microdosers. Odds-ratio testing was also used to compare rates of DSM-5 diagnostic categories and recent (past year) recreational substance use. For interpretability, analyses focused on participants who reported microdosing LSD, psilocybin, or both; other reported microdosing substances were coded but not emphasised in primary analyses.

The survey yielded an international sample of 909 respondents from 45 countries; of the 729 who reported country of origin, 50.1% were from the United States, 12.2% from Canada, and 5.1% from Norway. The overall sample was predominantly male (82.4%), with a mean age of 27.1 years (SD = 8.8, range 16–70) and 69.3% identifying as White/European. Comparing grouped microdosers (those reporting LSD and/or psilocybin microdosing) with non-microdosers, there were no significant differences in age, sexual orientation, ethnicity, social class, or highest completed education. Microdosers had significantly lower odds of reporting religious affiliation (OR = 0.46, 95% CI: 0.33–0.66) and a near-significant tendency to be male (OR = 1.47, 95% CI: 0.98–2.19). Among participants who reported microdosing, 59.3% reported using LSD (n = 385) and 25.9% reported using psilocybin-containing mushrooms (n = 168). Median self-reported microdoses were 13 mcg for LSD (reported as approximately 11.3% of one tab) and 0.3 g of dried psilocybin mushrooms. A multimodal distribution of dosing schedules emerged: the most common regimen was one-day-on, two-days-off (35.9% of microdosers, n = 136), followed by one-day-on, three-days-off (19.5%) and one-day-on, one-day-off (11.3%). The median monthly cost of microdosing was reported as USD 6.92. Regarding psychiatric history, 509 participants provided diagnostic data. Overall, 47.1% of microdosers (n = 154) and 54.0% of non-microdosers (n = 90) reported having received one or more psychiatric diagnoses in their lifetime. The most commonly reported diagnoses among microdosers were anxiety disorders (26.1%), mood disorders (24.6%), and ADHD (20.1%). Exploratory odds-ratio testing showed microdosers were significantly less likely than non-microdosers to report a history of substance use disorders (SUDs) (OR = 0.17, 95% CI: 0.05–0.56) and anxiety disorders (OR = 0.61, 95% CI: 0.41–0.91). No other diagnostic categories differed significantly between groups. Information on current prescription medications was provided by 496 respondents, 329 of whom were current or past LSD/psilocybin microdosers. After non-psychotropic medications, the most commonly reported psychotropic prescriptions among microdosers were stimulant medications (methylphenidate- or amphetamine-based; 6.4%), benzodiazepine receptor agonists or sedative-hypnotics (3.3%), bupropion (3.0%), and SSRIs/SNRIs (2.7%). On recreational substance use, microdosers reported high recent (past-month or past-year) use of several substances: cannabis (46.5%), full-dose classic psychedelics (45.5%), and MDxx compounds (31.1%). Grouped microdosers were approximately five times more likely to report recent recreational substance use (excluding caffeine, alcohol, nootropics, and prescription medications) than non-microdosers (OR = 5.2, 95% CI: 2.7–10.8). Specific elevated odds for microdosing status included full-dose classic psychedelics (OR = 5.49, 95% CI: 3.60–8.38), sedatives (OR = 2.73, 95% CI: 1.24–5.97), cannabis (OR = 2.61, 95% CI: 1.64–4.15), research chemical hallucinogens (OR = 2.42, 95% CI: 1.39–4.20), dissociatives (OR = 2.20, 95% CI: 1.33–3.64), inhalants (OR = 1.89, 95% CI: 1.03–3.47), and the MDxx family (OR = 1.80, 95% CI: 1.22–2.67). Microdosers were also modestly more likely to report ever having used recreational substances (OR = 1.48, 95% CI: 1.02–2.15).

Rosenbaum and colleagues interpret their findings as the most extensive descriptive dataset to date on self-reported psychedelic microdosing practices. They emphasise that LSD and psilocybin were the predominant substances reported, with median self-reported doses (13 mcg LSD; 0.3 g dried mushrooms) and a common dosing schedule of one-day-on, two-days-off. The authors note that the latter schedule may have a neurophysiological rationale related to tachyphylaxis at 5-HT2A receptors and that informal microdosing regimens appear to align with existing community recommendations and prior online surveys. Dose variability and ‘‘guess work’’—stemming from unstandardised fractions of illicit LSD tabs or variable psilocybin content in dried mushrooms—are highlighted as important practical limitations of current microdosing practice. The researchers point out that doses reported by participants may still produce notable subjective effects, citing prior experimental work that found doserelated effects at low LSD doses and evidence that even small psilocybin doses can produce meaningful phenomenology. For these reasons, they argue that controlled trials should test a range of doses and schedules, consider weight-based dosing, and use placebo controls to address expectancy effects. On psychiatric comorbidities, the authors observe that microdosers reported lower lifetime rates of SUDs and anxiety disorders compared with non-microdosers, while reporting higher rates of ADHD than population-level estimates. Several explanatory hypotheses are offered: individuals with prior SUDs or anxiety may avoid experimental practices like microdosing to reduce relapse risk or avoid anxiety-provoking uncertainty; alternatively, microdosers may be less likely to seek or receive SUD diagnoses despite higher recreational use. The high prevalence of ADHD among microdosers is noted as consistent with anecdotal claims that microdosing improves attention and concentration, and the authors call for placebo-controlled trials to evaluate such claims. The presence of ongoing psychotropic prescriptions among microdosers is seen as clinically relevant for trial design. The researchers flag potential pharmacodynamic interactions (for example, SSRIs attenuating psychedelic effects and theoretical risks such as serotonin syndrome) and discuss trade-offs in deciding whether study participants should taper medications before enrolment. They also stress that recent full-dose psychedelic use is a likely confounder when interpreting reported benefits of microdosing. Key limitations acknowledged by the authors include reliance on self-report, the self-selecting and potentially non-representative sample recruited primarily from psychedelics-oriented Reddit communities, and the inability to verify substance identity or dose. Despite these constraints, the authors regard their results as a substantive advance beyond media anecdotes and as a basis for designing rigorous safety and efficacy trials of psychedelic microdosing. Finally, the discussion contrasts microdosing with contemporary high-dose psychedelic therapy: microdosing resembles conventional pharmacotherapy in aiming to avoid overt altered states, which may simplify blinding and allow combination with standard psychotherapies. The authors recommend well-designed randomised controlled trials to test safety, tolerability, and efficacy, and to determine optimal dosing regimens and potential therapeutic indications.

The authors conclude that LSD and psilocybin are commonly used for microdosing and that their international sample of 909 respondents provides data that can inform future research. They emphasise that despite promising observational signals and widespread anecdotal use, controlled experimental research is required to evaluate safety, tolerability, and efficacy. The paper warns against widespread self-treatment with microdosing given the current lack of evidence and the potential for interactions with psychotropic medications, and calls for well-designed trials to test anecdotal claims and establish clinical guidance.