Medical Cannabis Laws Linked to Less Frequent Opioid Misuse

Medical cannabis laws were associated with a 1.5 percentage point decrease in frequent non-medical prescription opioid use and a 2.1 percentage point increase in occasional use, suggesting a shift in use patterns rather than overall reduction.

Multi-level mixed effects models analyzed nationally representative survey data from U.S. adults reporting past-year non-medical prescription opioid use across the 2004-2014 National Surveys on Drug Use and Health, comparing states with and without medical cannabis laws.

The opioid crisis has prompted interest in whether cannabis access might reduce opioid harms. This study suggests the relationship is more nuanced than simple substitution, with shifts in frequency patterns concentrated among people who also have cannabis use disorder.

This adds to a mixed evidence base on cannabis-opioid substitution. The finding that frequency shifts were driven by people with cannabis use disorder complicates the narrative that cannabis access broadly reduces opioid misuse. It raises questions about tradeoffs between reducing opioid harm and increasing cannabis-related risk.

Observational design cannot establish causation. Self-reported data from 2004-2014 may not reflect current cannabis markets. MCL implementation varied widely across states. The study could not assess specific products or doses used.