Psilocybin Smoking Cessation: Trial Results and Limitations
The evidence includes an unblinded randomized pilot published in 2026 and an earlier small uncontrolled programme. Compare the abstinence definition, comparator, follow-up and analysis population before interpreting the reported percentages.
Maintained by Dr. Christopher B. Germann · Primary sources checked .
Original educational annotations. This is a selected comparison, not an exhaustive systematic review, meta-analysis, clinical guideline or personal treatment recommendation. No independent clinical review is claimed.
Reports compared by population, design and endpoint
| Report and population | Design and sample | Endpoint and finding | Limitations |
|---|---|---|---|
| Johnson et al. · 2026 randomized pilot Psychiatrically healthy adult cigarette smokers | Open-label randomized comparison: one psilocybin session versus nicotine patches; both groups received manualized cognitive behavioral therapy 82 randomized: 42 psilocybin, 40 nicotine patch | Primary abstinence comparison favored psilocybin Biochemically verified prolonged abstinence at six months; intention-to-treat analysis 17/42 (40.5%) versus 4/40 (10.0%): odds ratio 6.12, 95% CI 1.99–23.26, p=0.003. Seven-day point-prevalence abstinence was a separate secondary endpoint. | Unblinded pilot at one centre, with different treatment contact time and a selected population. It does not compare against every established cessation treatment. No serious events were attributed to either intervention; this does not establish absence of rare harms. |
| Johnson et al. · 2014 pilot Nicotine-dependent smokers with previous quit attempts PubMed | Open-label single-group psilocybin programme with cognitive behavioral therapy 15 participants; no randomized comparator | Preliminary uncontrolled finding Biologically verified seven-day point-prevalence abstinence at six months 12/15 participants (80%) met this abstinence definition at six months. | A seven-day window does not mean continuous abstinence. Without a concurrent control, the contribution of psilocybin, therapy and selection cannot be separated. |
| Johnson et al. · 2017 follow-up The same 15-person cohort as the 2014 pilot PubMed | Longer follow-up of the earlier uncontrolled programme; not an independent trial 15 assessed at 12 months; 12 returned for later follow-up | Follow-up of the original cohort Biologically verified abstinence at 12 months and longer-term assessment 10/15 (67%) were abstinent at 12 months; 9/15 (60%) at longer follow-up, averaging 30 months after the target quit date. | Attrition and lack of a control remain. Counting this report and the 2014 pilot as separate participant cohorts would double-count evidence. |
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Abstinence definitions change the interpretation
Seven-day point-prevalence abstinence asks about a short window before an assessment. Prolonged abstinence covers a longer interval with a prespecified grace period. Neither should be substituted for the other when comparing percentages or planning an evidence synthesis.
The randomized study used intention-to-treat denominators and counted missing assessments as nonabstinent. Record the denominator and missing-data rule alongside an effect estimate. An odds ratio is not the same as a risk ratio or an absolute percentage-point difference.
The 2017 follow-up reports the earlier pilot cohort. An evidence table can include both reports, but participant counts must not be added as if they were separate trials. Check cohort overlap before any synthesis.
Addiction evidence remains substance-specific
Smoking abstinence, heavy drinking days and prevention of relapse after alcohol withdrawal answer different research questions. A result for tobacco does not demonstrate efficacy for opioid, stimulant or other substance use disorders.
The alcohol evidence guide includes both a positive drinking-outcome trial and an inconclusive relapse-prevention trial. Use the live addiction literature search for broader reports, while checking whether they are primary trials, reviews, protocols or preprints.
Safety and applicability
Screening, supervision, psychological support and follow-up are part of these research programmes. Recognizable drug effects can compromise blinding and influence expectations. Small selected samples provide limited information about rare harms and excluded populations.
Assess adverse-event definitions, denominators and observation periods in the original reports. An event occurring during follow-up is not automatically attributed to the intervention. Existing treatment and eligibility decisions require appropriate professional assessment.
Selection and source review
This guide selects a randomized tobacco pilot, an earlier uncontrolled pilot and its follow-up to support interpretation of a defined research question. Source verification on 9 October 2026 covered report identity, design, population and the outcomes summarized above. No publisher abstracts or instrument questionnaires are reproduced.
Coverage is bounded and may omit relevant or subsequent studies. Consult original articles, their corrections and supplementary methods before citing numerical results. Editorial policy · Data provenance and reuse · Compare selected findings.