Medical marijuana laws and mental health in the United States

The consequences of legal access to medical marijuana for individual welfare are a matter of controversy. We contribute to the ongoing discussion by evaluating the impact of the staggered introduction and extension of medical marijuana laws across US states on self-reported mental health. Our main analysis is based on BRFSS survey data from more than six million respondents between 1993 and 2015. On average, we find that medical marijuana laws lead to a reduction in the self-reported number of days with mental health problems. Reductions are largest for individuals with high propensities to consume marijuana for medical purposes and people who are likely to suffer from chronic pain. Moreover, the introduction of prescription drug monitoring programs lead to a reduction in bad mental health days only in states that allow medical marijuana.