Cannabis and Cannabinoids Alter the Gut Microbiome with Both Beneficial and Harmful Effects

Nine studies (2 clinical trials, 7 observational) examined cannabis/cannabinoid effects on oral, GI, fecal, and vaginal microbiota. Positive associations: serum endocannabinoids correlated with beneficial gut microbiota via elevated SCFAs and anti-inflammatory actions. In HIV patients, marijuana use reduced pro-inflammatory Prevotella. Negative associations: excessive consumption reduced microbial richness and diversity with increased systemic inflammation.

Systematic review searching PubMed, Embase, and Cochrane Library CENTRAL. Included studies on marijuana, medical cannabis, cannabinoids, and cannabinoid-like lipid mediators across all clinical conditions and body sites.

The microbiome is increasingly recognized as central to health and disease. Understanding how cannabis affects it is essential for evaluating the full impact of cannabis use and developing microbiome-based therapeutic strategies.

The dual nature of cannabis-microbiome interactions — beneficial at moderate levels but potentially harmful with heavy use — mirrors the dose-dependent pattern seen in many cannabis health outcomes. This adds the microbiome as another dimension to consider in cannabis risk-benefit assessments.

Very small evidence base (9 studies). Heterogeneous clinical contexts, cannabis products, and microbiome assessment methods. Cannot determine causation in observational studies. Different body sites make cross-study comparison difficult.