Evidence Lacking on Benefits of Cannabis for Treating Chronic Pain or PTSD

By Kelly Young

Edited by David G. Fairchild, MD, MPH, and Jaye Elizabeth Hefner, MD

Evidence is limited on the benefits of cannabis use for treating chronic pain and post-traumatic stress disorder, according to two reviews in the Annals of Internal Medicine.

The review on chronic pain included 75 studies that examined the potential benefits and harms of cannabis use. There was low-strength evidence that cannabis could help ease neuropathic pain in some patients, based primarily on studies of nabiximols (oral spray containing tetrahydrocannabinol plus cannabidiol). The authors found insufficient evidence to make a conclusion about other forms of pain. In terms of potential harms, some evidence suggested that daily use may lead to adverse pulmonary effects over time.

A separate review of five studies found a dearth of evidence on cannabis's benefits and harms in PTSD.

An editorialist concludes: "Even if future studies reveal a clear lack of substantial benefit of cannabis for pain or PTSD, legislation is unlikely to remove these conditions from the lists of indications for medical cannabis. It will be up to front-line practicing physicians to learn about the harms and benefits of cannabis, educate their patients on these topics, and make evidence-based recommendations about using cannabis and related products for various health conditions. […] In this context, these reviews are must-reads for all physicians, especially those practicing in states where medical cannabis is legal."

Links:

Annals of Internal Medicine article on chronic pain (Free)

Annals of Internal Medicine article on PTSD (Free)

Annals of Internal Medicine editorial (Subscription required)

Background: NEJM Journal Watch Psychiatry coverage of cannabis use and lifespan (Your NEJM Journal Watch registration required)