A 20-year Australian study has found no evidence to suggest cannabis reduces illicit opioid use, and it may not be an effective long-term method of reducing harm for those with an opioid use disorder or problematic use of opioids.
Published in the American Journal of Psychiatry, the University of Sydney-led study is one of the longest of its kind.
Between 2001 to 2022, the study involved a group of 615 people with heroin dependence, many of whom also used cannabis.
Additional analysis also found no consistent evidence between cannabis and other opioid use, including opioids that were prescribed.
Opioid use is currently responsible for more death and disability than any other illicit drug. Opioid and cannabis use disorders make up approximately 77 percent of all illicit drug disorders.
The researchers say clinicians and policymakers should be cautious about relying on cannabis to reduce problematic opioid use or as a potential strategy to help manage the opioid crisis, especially given a global shift towards cannabis legalization and recognition as a therapeutic product.