Importance: Mental health disorders are prevalent yet undertreated health conditions in the US. Given perceptions about the potential effect of cannabis on individuals with mental health disorders, there is a need to understand the association of cannabis laws with psychotropic use.

Question: Is access to cannabis, via medical or recreational legalization, associated with changes in dispensing of prescription medications to treat mental health disorders in a commercially insured population?

Findings: This cross-sectional study of 9 438 716 commercially insured patients found statistically significant reductions in benzodiazepine dispensing after increases in both medical and recreational cannabis access. However, evidence suggests increases in other types of psychotropic dispensing.

Meaning: This study suggests that cannabis laws may be significantly associated with the population-level use of prescription drugs to treat mental health disorders, although the associations vary by drug class and state.