Benefits and Harms of Cannabis in Chronic Pain or Post-traumatic Stress Disorder: A Systematic Review

"We found no observational studies that met inclusion criteria, but a growing body of cross-sectional literature suggests negative opioid-related correlates among individuals who use cannabis and opioids concurrently. These include opioid misuse;9,10,99,133 a greater number of opioid refills;99 a longer duration of opioid use; a higher dose of opioid medication prescribed;9 and endorsement of using opioids and other pain medications without a prescription.134"