Published summary: 2026-03-07
Where the evidence converges
PATH Study analysis of 8,218 cigarette smokers found cannabis co-use (reported by 36%) was associated with 19% lower odds of quitting smoking and 25% lower odds of quitting all combustible tobacco
Moderate evidence · 5 studies
Based on limited number of strong-evidence studies.
Analysis of 15 years of national data showing cannabis-using smokers are significantly more responsive to cigarette price increases than non-cannabis-using smokers
Moderate evidence · 5 studies
Based on limited number of strong-evidence studies.
Where questions remain
Nearly half of young adult cannabis users mixed tobacco with cannabis, and more frequent mixing was associated with greater nicotine dependence
Moderate evidence · 5 studies
Self-reported measures. Longitudinal design but nicotine dependence analysis was cross-sectional within the cannabis-using subsample. Canadian context where mixing may be more common than in the U.S.
Among 45,151 tobacco quitline callers, 27% also used cannabis and had lower 7-month smoking quit rates (23% vs 29%), though 43% of co-users wanted to quit cannabis too
Moderate evidence · 5 studies
Observational data from a single state quitline. Self-reported outcomes may overestimate quit rates. The association between co-use and lower quit rates could reflect shared underlying risk factors ra
Analysis of 2,267 young adults identified five cannabis-tobacco use patterns, with the heaviest poly-product users disproportionately representing populations facing substance use disparities
Moderate evidence · 5 studies
Purposively recruited sample overrepresenting cannabis users. Facebook recruitment may miss some demographics. Cross-sectional design. Self-reported use. Class assignments are probabilistic, not defin
Survey of 1,402 tobacco retailers found THC and CBD each available in about 10% of stores across three US cities, with e-cigarette and cigar stores most likely to carry cannabinoids regardless of local cannabis policy
Moderate evidence · 5 studies
Cross-sectional survey at one timepoint. Product availability does not measure actual sales or co-use. Cannot determine if products were legal hemp-derived vs. illicit THC. Three cities may not repres
Research gaps
- Only 0 randomized controlled trials exist out of 23 studies — most evidence is observational or from reviews.
- Sex-specific differences in this area remain understudied.
- With only 23 studies, this remains an emerging research area where conclusions should be considered preliminary.
- Long-term prospective studies tracking outcomes over 5+ years are largely absent from the literature.
- Research on diverse populations (different ages, ethnicities, and medical backgrounds) remains limited.
Key studies
Adding Cannabis to Alcohol During Pregnancy Increases Risk of Small Babies
This is one of the first large studies to isolate cannabis's additive effect on birth outcomes beyond alcohol — showing that polysubstance use compounds risk in measurable, clinically significant ways.
8% of Americans Co-Use Tobacco and Cannabis — Here's How They Do It
Co-use of tobacco and cannabis compounds health risks (as shown by RTHC-08179), and understanding how people combine these substances is essential for prevention. The age-based differences in administration routes suggest different intervention approaches are needed for different generations.
Cannabis Legalization Drives Up Tobacco-Cannabis Co-Use While Reducing Tobacco-Only Use
While legalization reduces tobacco-only use, the simultaneous increase in tobacco-cannabis co-use — which combines the health risks of both substances — represents an unintended consequence that public health responses must address.
Cannabis Co-Use Made Smokers Less Likely to Quit Cigarettes
As cannabis becomes more accessible, the proportion of cigarette smokers who also use cannabis is growing. This study reveals a previously underappreciated barrier to tobacco cessation: cannabis co-use may reduce the likelihood of quitting smoking, complicating public health efforts to reduce tobacc
Cannabis Users Are More Sensitive to Cigarette Price Increases Than Non-Users
As cannabis use rises and cigarette smoking declines, understanding how these markets interact helps design more effective tobacco control policy. If co-users are more price-sensitive, tobacco taxes provide extra benefit for this growing subgroup.
Treating Alcohol Addiction Also Reduces Cannabis and Cigarette Use — Even When That's Not the Goal
The finding that treating one substance problem can ripple across others challenges the single-substance treatment model — and suggests comprehensive substance use screening should be standard in addiction trials.
How the research developed
2020–present
23 studies published. Includes 5 strong-evidence studies.
How this summary was assembled
This consensus synthesizes 23 peer-reviewed studies: 13 observational studies (57%), 10 other study types (43%). Studies span from the earliest available research through 2025. Evidence strength ratings reflect study design, sample size, and replication across multiple research groups.
These counts describe the source summary at publication. They may differ from the current library.