“The findings provide a granular view of patient patterns of medical cannabis use, and the subsequent self-reported impacts on the use of opioids, alcohol, and other substances, adding to a growing body of academic research suggesting that increased regulated access to medical and recreational cannabis can result in a reduction in the use of and subsequent harms associated with opioids, alcohol, tobacco, and other substances.”

https://www.ncbi.nlm.nih.gov/pubmed/30691503

https://harmreductionjournal.biomedcentral.com/articles/10.1186/s12954-019-0278-6