“Growing nonmedical use of prescription opioids is a global problem, motivating research on ways to reduce use and combat addiction.
Medical cannabis (“medical marijuana”) legalization has been associated epidemiologically with reduced opioid harms and cannabinoids have been shown to modulate effects of opioids in animal models.
This study was conducted to determine if Δ9-tetrahydrocannabinol (THC) enhances the behavioral effects of oxycodone.
Together these data demonstrate additive effects of THC and oxycodone and suggest the potential use of THC to enhance therapeutic efficacy, and to reduce the abuse, of opioids.”
https://www.ncbi.nlm.nih.gov/pubmed/30980837
“Δ9-tetrahydrocannabinol (THC) enhances the antinociceptive effects of oxycodone. Vaporized and injected THC reduces oxycodone self-administration. Cannabinoids may reduce opioid use for analgesia. Cannabinoids may reduce nonmedical opioid use.”
https://www.sciencedirect.com/science/article/pii/S0028390819301212?via%3Dihub