News release

From: American College of Physicians

Cannabis-based products show limited short-term benefit for chronic pain, with increased risk of adverse effects

Products with higher THC concentration show more improvements in pain severity compared to CBD-only products

A systematic review of trials including more than 2,300 adults with chronic pain found that cannabis-based products with higher tetrahydrocannabinol (THC)-to-cannabidiol (CBD) ratios may provide small short-term improvements in pain and function, especially for those with nerve pain. However, these products are also associated with increased risks of common adverse events. Products with a low THC-to-CBD ratio, including CBD-only formulations, did not appear to be helpful. The review is published in Annals of Internal Medicine.

Researchers from Oregon Health & Science University and colleagues analyzed 25 short-term placebo-controlled randomized trials of cannabis products to update previous evidence about the effectiveness and harms of cannabis-based products for treating chronic pain. The researchers categorized cannabinoids by the ratio of THC to CBD (high, comparable, low); whether the product was synthetic, purified, or extracted from a plant; and administration method (oral, oromucosal, topical) and assessed how well they reduced pain, improved function and whether there were any adverse events. The data showed that oral THC-only products probably slightly reduce pain severity, with the cannabinoids nabilone demonstrating a moderate effect and dronabinol showing no or trivial effect. Nabiximols slightly reduced pain severity and had no meaningful effect on function. Across trials, high and comparable THC products were linked to moderate-to-large increases in adverse events including dizziness, sedation, and nausea. The review highlights the need for more research on long-term outcomes and other cannabis product types.

An accompanying editorial from the UCLA Center for Cannabis and Cannabinoids says the review highlights both the promise and limitations of cannabinoids in treating chronic pain. While THC-based products may offer modest relief, inconsistent study results and safety concerns underscore the need for further research to guide patients, clinicians, and policymakers.