Psychiatry · Medical Literature
[Corrections] Correction to Lancet Psychiatry 2026; 13: 304–15
Abstract
Wilson J, Dobson O, Langcake A, et al. The efficacy and safety of cannabinoids for the treatment of mental disorders and substance use disorders: a systematic review and meta-analysis. Lancet Psychiatry 2026; 13: 304–15—In this Article the spacing of the x-axis of figure 2 has been corrected and in table 1 anxiety disorders for THC only classification should have been 1, anxiety disorders for CBD only classification should have been 5, ASD for CBD only classification should have been 0, ASD for combined THC and CBD classification should have been 2, ASD for follow-up ≤1 month should have been 0, and ASD for follow-up >1 month should have been 2.
Clinical relevance
In adults with mental disorders or substance use disorders (SUDs), do cannabinoids (THC, CBD, or combined formulations) demonstrate efficacy and an acceptable safety profile as primary pharmacological treatments compared with placebo or active control in randomized controlled trials? __SNAPSHOT__ {"studyDesign":"Systematic review and meta-analysis of randomized controlled trials (RCTs); PROSPERO preregistered","setting":"International; multi-database search (Ovid MEDLINE, PsychINFO, Cochrane CENTRAL, Cochrane Database of Systematic Reviews, Embase); publications from 1980 to May 2025","sampleSize":"54 RCTs included; 2,477 participants (screened from 5,774 studies)","population":"Adults with mental disorders (including anxiety disorders, major depressive disorder, PTSD, psychotic disorders, ADHD, autism spectrum disorder [ASD], sleep disorders, OCD, anorexia nervosa, Tourette's syndrome) or SUDs (cannabis use disorder, opioid use disorder, cocaine use disorder). Reported sample was 69% male, median age 33 years.","intervention":"Plant-based or pharmaceutical cannabinoids as primary treatment: THC alone (n=18 trials), CBD alone (n=24 trials), or combined THC+CBD formulations (n=12 trials)","comparator":"Placebo or active control (as reported per individual RCT)","primaryOutcome":"Efficacy (symptom improvement across diagnoses) and safety (adverse events, serious adverse events, study withdrawal rates) of cannabinoids as primary treatment for mental disorders and SUDs","followUp":"Stratified by ≤1 month and >1 month; overall follow-up duration not reported as a single pooled figure","fundingSource":"Government (National Health and Medical Research Council [NHMRC] of Australia; GNT2017346, GNT2030765); some authors received WHO consultation fees and Therapeutic Goods Administration funding for separate evidence reviews — see conflict-of-interest note below"}
Key findings
Across 54 RCTs (2,477 participants), cannabinoids did not demonstrate significant efficacy for anxiety disorders, major depressive disorder, PTSD, psychotic disorders, OCD, anorexia nervosa, or opioid use disorder. Cannabinoids were associated with increased cocaine craving relative to placebo (effect size not reported in available abstract). The most robust efficacy signals — characterized by the authors as limited rather than established — were observed for cannabis use disorder (THC+CBD combinations), ASD symptom reduction, insomnia (any cannabinoid), and Tourette's syndrome (THC+CBD combinations); however, the overall quality of evidence was rated as low. On safety: serious adverse events and study withdrawal rates did not differ significantly between cannabinoids and controls across conditions. The overall odds ratio for all-cause adverse events was 1.75 (95% CI 1.25–2.46), indicating a statistically significant increase in any adverse event with cannabinoid use versus control. NNT and NNH were not calculable from the available abstract data. A post-publication correction (June 16, 2026) revised specific trial-classification counts in Table 1 (figure 2 x-axis spacing; anxiety disorders THC-only count corrected to 1; CBD-only count corrected to 5; ASD CBD-only count corrected to 0; ASD combined THC+CBD count corrected to 2; ASD follow-up ≤1 month corrected to 0; ASD follow-up >1 month corrected to 2) — these corrections affect subgroup categorization but the primary conclusions of the review were not altered by the erratum.
Practice implications
This is the largest RCT-only meta-analysis of cannabinoids for mental disorders and SUDs to date, and its primary finding is an absence of demonstrated efficacy for the most prevalent conditions for which cannabinoids are currently prescribed — anxiety, depression, and PTSD. Clinicians should note that 'absence of evidence of benefit' in a systematic review of limited, heterogeneous trials is not equivalent to 'evidence of absence of benefit'; however, the burden of proof for clinical prescribing rests on demonstrated efficacy, not on the absence of disconfirming trials. The findings apply most directly to adults receiving standardized pharmaceutical-grade THC, CBD, or combined cannabinoid products in controlled trial conditions; they do not reflect real-world self-medication with variable-potency commercial cannabis products, which were explicitly excluded. Populations systematically underrepresented include females (only ~31% of the pooled sample), children and adolescents, individuals with complex comorbidities, and patients using high-potency variable-ratio products typical of non-pharmaceutical markets. The modest signals for benefit in cannabis use disorder (THC+CBD), ASD, insomnia, and Tourette's syndrome are based on a small number of trials rated as low-quality evidence and should not be considered sufficient for practice-changing recommendations without replication in larger, adequately powered trials. The post-publication correction to Table 1 and Figure 2 does not alter the primary efficacy or safety conclusions but does affect ASD subgroup classification counts; clinicians using this data for ASD-specific clinical decisions should consult the corrected version published June 16, 2026. Only the abstract was accessible for this summary; full methods, individual forest plots, GRADE certainty ratings per condition, and heterogeneity statistics (I²) were not available for review and represent a limitation of this teaching summary. __LIMITATIONS__ 1. Evidence base restricted to RCTs only: excludes observational and real-world data, limiting generalizability to patients with complex comorbidities and non-pharmaceutical cannabis products. 2. High heterogeneity anticipated across 54 trials spanning 45 years, multiple conditions, cannabinoid types, doses, and formulations — I² values not available from abstract. 3. Small aggregate sample size (n=2,477 across all conditions and cannabinoid types) is underpowered for condition-specific subgroup conclusions. 4. Most RCTs tested standardized pharmaceutical cannabinoids at fixed doses, not the high-THC variable-ratio products patients most commonly use. 5. Low quality of evidence rated overall — likely driven by small trial sizes, risk of bias, and imprecision. 6. Post-publication correction to trial classification data in Table 1 (ASD and anxiety disorder subgroups) introduces uncertainty about subgroup analyses prior to the June 16, 2026 corrected version. 7. Sex imbalance (69% male) limits applicability to female patients. 8. Surrogate or condition-specific symptom scales used as primary outcomes across trials; clinical meaningfulness of pooled effect sizes across different instruments is uncertain. 9. Publication bias cannot be fully excluded given relatively small number of included trials per condition. 10. Some co-authors have received fees from WHO and Therapeutic Goods Administration, though primary funding was government (NHMRC) with no direct industry sponsorship declared. __BOTTOM_LINE_CATEGORY__ potentially_practice_informing __BOTTOM_LINE__ This landmark systematic review and meta-analysis of 54 RCTs found no significant evidence that cannabinoids (THC, CBD, or combined) improve outcomes in anxiety, depression, PTSD, psychotic disorders, OCD, anorexia nervosa, or opioid use disorder, while cannabinoids were associated with a statistically significant increase in all-cause adverse events (OR 1.75, 95% CI 1.25–2.46). Modest signals favoring cannabinoids in cannabis use disorder, ASD, insomnia, and Tourette's syndrome are based on low-quality evidence and require confirmation before influencing prescribing practice. A June 2026 erratum corrected trial-classification counts for ASD and anxiety disorder subgroups in Table 1; clinicians should reference the corrected version and should not cite pre-correction subgroup counts.