Clinical Edge

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Cannabis for the Treatment of Chronic Pain

Ann Intern Med; ePub 2017 Aug 15; Nugent, et al

Cannabis may alleviate neuropathic pain among adults but is also associated with an increase in adverse mental health effects, according to limited evidence from a recent systematic review. The review examined the benefits of plant-based cannabis preparations for treating chronic pain in adults and the harms of cannabis use in chronic pain and general adult populations. Among the findings:

  • In 27 chronic pain trials, cannabis may alleviate neuropathic pain (low-strength evidence) but there was insufficient evidence in other pain populations.
  • According to 11 systematic reviews and 32 primary studies, harms in the general population studies include increased risk for motor vehicle accidents, psychotic symptoms, and short-term cognitive impairment.
  • Adverse pulmonary effects were not seen in younger populations.
  • Evidence on most other long-term physical harms, in heavy or long-term cannabis users, or in older populations is insufficient.

Citation:

Nugent SM, Morasco BJ, O'Neil ME, et al. The effects of cannabis among adults with chronic pain and an overview of general harms: A systematic review. [Published online ahead of print August 15, 2017]. Ann Intern Med. doi:10.7326/M17-0155.

Commentary:

Twenty-eight states have legalized cannabis for medical use, so understanding the efficacy and safety of cannabis use is of increasing importance.1 Over half of all patients who seek cannabis for medical use do so for the relief of chronic pain.2 This review shows that cannabis may have some efficacy for pain, but that the evidence suggests only a mildly beneficial effect on pain, and that the available evidence is drawn from low-quality studies. We also see an increased risk of motor vehicle accidents and cognitive impairment. In thinking about this new treatment, it is likely that the direct effect of cannabis is less than that of other traditional pain medications, so should not take the place of more carefully studied pain medications, but instead may have a place for selected patients as an adjuvant treatment for pain. —Neil Skolnik, MD

  1. National Conference of State Legislatures. Marijuana overview. www.ncsl.org/research/civil-and-criminal-justice/marijuana-overview.aspx. Accessed May 19, 2017.

  2. Ilgen MA, Bohnert K, Kleinberg F, et al. Characteristics of adults seeking medical marijuana certification. Drug Alcohol Depend. 2013;132:654-659. doi:10.1016/j.drugalcdep.2013.04.019.