In July, a user on the popular social media forum Reddit posed a simple but charged question: “Does cannabis help?”
Posted to r/OpiatesRecovery, a 56,000‑member forum for people recovering from opioid addiction, the question drew mixed responses within minutes.
Some said they found it helpful; others cited cannabis’ negative side effects.
For cannabis and psychedelics researcher Philippe Lucas, the question is not hypothetical.
In the early 2000s, when Lucas ran a non-profit medical cannabis dispensary in Victoria, B.C., he routinely heard patients say cannabis had helped them stay away from more harmful drugs.
“They would tell me … that they actually found when they ate a cannabis cookie, they didn’t feel like looking for opioids,” said Lucas, who is the director of research and safe access at the Multidisciplinary Association of Psychedelic Studies (MAPS) and a research affiliate at the University of Michigan’s Psychedelic Center.
“Or when they smoked a joint, they didn’t feel like looking for crystal meth or other drugs.”
Lucas is one of a growing body of researchers and cannabis users who say cannabis has the potential to be a low-barrier harm-reduction option. But health authorities so far say the evidence is too inconclusive to inform clinical guidance.
Treatment pathways
The World Health Organization estimates that about 60 million people globally struggle with opioid addiction.
Within Canada, about 10 per cent of the 3.7 million Canadians who used opioid medication in 2018 reported problematic use, according to Statistics Canada.
Opioid use disorder is typically treated with medication-assisted therapies such as buprenorphine (e.g. Suboxone or Sublocade), methadone or morphine that reduce cravings and withdrawal symptoms.
Canadian clinical guidelines currently do not mention cannabis as part of any treatment pathway for opioid use disorder.
Even so, some people are turning to cannabis to help manage their opioid use — particularly if traditional opioid treatments have negative side effects, are ineffective or are hard to access.
Emerging research supports this practice.
A 2018 Vancouver study found daily cannabis use was linked to a greater likelihood of staying in treatment for opioid addiction over time.
A 2019 survey, led by Lucas while working with cannabis company Tilray, found many Canadians who were prescribed medical cannabis substituted it for opioids.
A 2020 Vancouver study found that people using cannabis while on methadone or buprenorphine were less likely to use fentanyl. (One of the authors, M-J Milloy, held the Canopy Growth Professorship in Cannabis Science at the University of British Columbia, which is funded by the cannabis company Canopy Growth.)
“Data seems to be overwhelmingly in favour of the potential for cannabis to act as a safer substitute for opioids, whether that be in a medical setting or in a recreational, non-medical setting,” said Lucas.
Lucas views cannabis not as a panacea, but as a lower-risk option worth considering — especially for those who struggle with standard treatments.
“Opioid agonist therapies, particularly methadone, are still dependence-forming,” he said. “And long-term use [of these therapies] does lead to more significant [adverse] health outcomes,” he said.
“We don’t tend to see the same kind of deleterious effects from cannabis over long-term patterns.”
Bias
However, the cannabis industry’s role in funding cannabis-related research has raised concerns about some studies’ objectivity.
Several studies led by Lucas — including a 2021 Pain Medicine paper and a 2024 study in Cannabis journal — were funded by cannabis company Tilray. In one study, participants self-selected to use the company’s products and received product discounts.
Lucas says that disclosures were transparent and that the incentives were a practical way to retain participants in long-term studies. “Research costs money … and therefore [researchers] are maybe biased towards looking for harms or benefits,” he said.
“The one thing that we can do as academics is ensure that our research designs are not biased.”
A 2023 Vancouver study led by the British Columbia Centre on Substance Use found cannabis use was associated with reductions in illicit opioid use. The centre has also accepted funding from the cannabis industry, Canadian Affairs previously reported.
However, there is some independent research that echoes the findings of industry-funded research.
A 2021 Danish study and a 2021–2022 U.S. study, both led by academic researchers, found cannabis helped patients reduce opioid use and manage withdrawal symptoms, especially among those with chronic pain.
Weak evidence
Despite growing interest in cannabis as a potential aid in treating opioid use disorder, health authorities remain cautious.
A 2022 review by Canada’s Drug Agency concluded that the existing evidence base is inconsistent, low quality and indeterminative. The new federal agency evaluates drugs to offer health policy recommendations.
“The 2022 rapid review identified a lack of consensus in the literature at the time whether cannabis was beneficial or detrimental,” a spokesperson for the agency told Canadian Affairs in an email.
The agency’s report concluded that any future consideration of cannabis’ treatment benefits must be held to rigorous standards of efficacy, safety and comparative effectiveness — just like other opioid use disorder treatments.
Similarly, a 2019 McMaster review found that the quality of evidence linking cannabis use to reduced opioid use or improved retention in methadone treatment was very low. The authors called for further research.
It just depends
Personal experiences with cannabis as a tool for opioid recovery are as varied as the people who use it.
In an anonymous Reddit discussion, some users described cannabis as a crucial aid during early recovery from opioid addiction.
“It was an active, anti-relapse mechanism for me,” one user wrote.
Another user described anxiety and lethargy, and warned that “weed addiction can have more bad consequences than people realize.”
Canadian Affairs has previously reported on the potential health risks of heavy cannabis use, including severe and repeated bouts of vomiting, psychosis and schizophrenia, cardiovascular problems and even increased mortality.
Others said that some cannabis strains helped manage their pain and calm their mind, but noted that long-term use was not sustainable or effective for everyone.
These conflicting views mirror what Lucas has seen in his research and community work: cannabis is not effective for everyone, but its harm reduction potential should not be overlooked.
“Even recreational users tend to cite a level of self-healing … like improved sleep, reduced stress, reduced anxiety,” he said.
“[Ultimately] you’re going to want to make sure that your use is leading to positive outcomes in your life, rather than negative outcomes.”
“There is a modest risk of dependence,” he added. “But luckily … people are normally able to successfully give up cannabis without going through formal [addiction] treatment.”
