Cannabis and pain: A review.

Cannabis and cannabis derivatives are sometimes used to relieve pain.

OBJECTIVE:

To conduct a scoping review to explore the extent of the literature on the efficacy, safety, and side effects of cannabis and cannabis derivatives as a treatment for pain.

METHODS:

The English-language literature was searched using electronic databases for studies published from 1960 to August 15, 2016. All randomized controlled trials that compared cannabis to a control and that examined pain as an outcome were included. Data on demographic and clinical characteristics, study duration, intervention duration, and outcomes were abstracted.

RESULTS:

Of 4,472 articles identified through the literature search, only 28 studies satisfied eligibility criteria. An additional 5 were identified through hand search Most studies had very small sample sizes. The primary methods of administration were oromucosal spray of nabiximol, oral ingestion of cannabis extract capsules, and inhalation of smoked cannabis. Overall, nabiximol oromucosal sprays resulted in reductions in pain that were statistically significant but of variable clinical relevance. Studies of oral cannabis extracts nabilone and dronabinol yielded mixed results, with some studies demonstrating effectiveness and others being negative. Studies of smoked cannabis consistently demonstrated statistically significant and clinically relevant reductions in neuropathic pain.

CONCLUSIONS:

Published research on the efficacy of cannabis as a treatment for pain is extremely limited. Evidence of effectiveness was strongest for smoked cannabis for neuropathic pain.