There has been interest in cannabis being used as a replacement drug for people with opioid use disorder, but research at McMaster University has found it doesn't work.
The research team looked at all research on the effects of cannabis use on illicit opioid use during methadone maintenance therapy, which is a common treatment for opioid use disorder, and found six studies involving more than 3,600 participants.
However, a meta-analysis of the studies found cannabis use didn't reduce illicit opioid use during treatment nor did it retain people in treatment.
The study was published today in the Canadian Medical Association Journal.
"There is limited evidence that cannabis use may reduce opioid use in pain management, and some high-profile organizations have suggested cannabis is an 'exit drug' for illicit opioid use, but we found no evidence to suggest cannabis helps patients with opioid use disorder stop using opioids," said senior author Dr. Zainab Samaan, associate professor of psychiatry and behavioural neurosciences at McMaster and a Hamilton staff psychiatrist.
The study was funded by the Canadian Institutes of Health Research.