Does Medical Cannabis Reduce Use of Prescription Opioids?

Is the solution to the opioid epidemic as simple as the legalization of medical cannabis? Commenting on the Bachhuber et al. analysis (1), Finney et al. (4) cautioned that an ecological fallacy may be present—individuals using medical marijuana could have elevated overdose mortality rates even though there is a state-level reduction. They contended that a prospective study of individual pain patients was necessary to assess relationships between cannabis use, use of opioid medications, and other substance use (4).