A new study published in Preventive Medicine Reports found that medical marijuana dispensaries and recreational marijuana legalization were associated with significant reductions in nonfatal opioid poisonings among adults with employer-sponsored health insurance.

The study, conducted by researchers from the University of Kentucky, examined data from more than 107 million enrollees ages 18 to 64 in the Merative MarketScan Commercial Claims and Encounters Database from 2011 through 2021. Researchers compared states before and after the adoption of various marijuana policies, including medical marijuana legalization, medical marijuana dispensary openings, home cultivation laws and recreational legalization.

Researchers found that states with medical marijuana dispensaries saw a 15.47% reduction in nonfatal opioid poisonings per 100,000 enrollees per quarter. Recreational marijuana legalization was associated with an 11.92% reduction.

The reductions linked to medical marijuana dispensaries were significant among both men and women, as well as adults ages 18 to 34. Researchers also found significant reductions among people without opioid prescriptions in the past year, those without cannabis use disorder diagnoses and those receiving outpatient services.

Medical marijuana legalization by itself and home cultivation laws were not associated with significant reductions in nonfatal opioid poisonings.

The authors said the findings suggest expanded access to marijuana through dispensaries and adult-use legalization may be linked to lower rates of nonfatal opioid poisonings, particularly among younger adults and men, two groups heavily affected by the opioid crisis. They cautioned that the study could not determine whether individuals directly substituted marijuana for opioids, and said the findings may not apply to people outside the employer-sponsored insurance population.

The study concludes that marijuana legalization should be viewed as complementary to evidence-based opioid use disorder treatment, with policymakers continuing to prioritize harm reduction and treatment expansion.