The current evidence for the efficacy and safety of replacing opioids with medical cannabis for treating opioid addiction does not meet standards for recommendation and is potentially harmful, according to a study published in JAMA.

The authors of this study sought to assess the safety and comparative effectiveness of medical cannabis as an opioid substitute for treating chronic pain or addiction.

Study investigators systematically searched for recent studies on the use of cannabis to treat chronic pain and opioid use disorder. The authors identified low-strength evidence that plant-based cannabis preparations may alleviate neuropathic pain. However, these studies involved small sample sizes, short follow-up periods, and were mostly of low methodological quality. The authors also found no prospective evidence in support of medical cannabis for treating patients with opioid addiction.

Currently, no randomized clinical trials have been performed to study the effect of substituting cannabis for opioids in patients taking or misusing opioids to relieve pain. Other studies linking cannabis with fewer opioid overdoses are limited in their methodology, in which causation cannot be inferred. The largest prospective study on cannabis as a substitute for opioids associated cannabis use with more subsequent pain, less self-efficacy for managing pain, and no reductions in prescribed opioid use. In other words, there was no substitution.

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The authors suggested that recommending cannabis to treat people with opioid addiction when no clinical trials have been performed reflects the stigmatized nature of treating addiction. Cannabis is not associated with risk for fatal overdose, however, the danger of substituting cannabis to prevent or treat addiction may be associated with greater risk of developing cannabis or other substance use disorders.

Although it merits further research, medical cannabis recommendations should not be made without the appropriate evidence base — which other preparations of medications are subject to — especially when other evidence-based therapies are available.  

Disclosures: One author reports receiving fees from varied associations, universities, and hospitals. See the reference for complete disclosure information.

Reference

Humphreys K, Saitz R. Should physicians recommend replacing opioids with cannabis? [published online February 1,2019]. JAMA. doi:10.1001/jama.2019.0077