Some THC products may improve chronic pain in the short term, review finds

Certain cannabis-based products convey limited short-term benefits for chronic pain but are associated with a higher risk for dizziness, sedation, and nausea, a review of 25 randomized controlled trials found.

To better understand the benefits and harms of cannabinoids for chronic pain, researchers searched databases for relevant randomized placebo-controlled trials published up to July 2025. Cannabinoids were classified based on their tetrahydrocannabinol (THC)-to-cannabidiol (CBD) ratio—high (≥2:1), comparable (1:2), or low (≤1:2)—as well as their source (synthetic, purified, extracted) and administration method. A total of 25 short-term (one- to six-month) randomized controlled trials (64% on neuropathic pain) involving 2,303 patients were included. Across all trials, mean age ranged from 24 to 68 years, and mean baseline pain scores ranged from 2.5 to 8.5 on a 0 (no pain) to 10 (worst pain imaginable) scale. Findings were published by Annals of Internal Medicine on Dec. 23.

Oral synthetic/purified high THC-to-CBD (THC only) and oromucosal, extracted, comparable THC-to-CBD ratio products may slightly reduce pain severity (pooled differences, 0.78 and 0.54 points, respectively), the review found. However, low- and moderate-level evidence supported a moderate to large increase in risk for adverse events with THC versus placebo, including dizziness, sedation, and nausea. An analysis of THC-only products found that nabilone moderately reduced pain severity but dronabinol did not (pooled differences, −1.59 and −0.23 points, respectively). In addition, studies suggested that low THC-to-CBD ratio products may not improve outcomes and low THC-to-CBD ratio mixed THC/CBD products may increase dizziness, sedation, and nausea. Products with CBD alone may not increase harms, the review found.

Limitations included lack of product details, unclear U.S. availability of studied products, and inclusion of only English-language studies.

“Although the observed benefits of high and comparable THC-to-CBD products seem similar to benefits observed in placebo-controlled [randomized controlled trials] of nonsteroidal anti-inflammatory drugs and opioids for chronic pain, such comparisons are indirect and head-to-head trials are needed,” the researchers wrote. They also called for more studies on long-term outcomes and additional cannabis product types.

An accompanying editorial lauded the research, calling it the most comprehensive review on the subject to date, but pointed out most studies in the review involved synthetic cannabinoids as opposed to plant-derived products that may be similar to those available in dispensaries, raising the question of generalizability. “The rapidly evolving marketplace and increase in use require a shift in focus from understanding whether a single cannabinoid preparation is safe and effective to understanding under what conditions cannabis-based products can be used safely, whether they confer meaningful benefit, and how risks can be minimized,” the editorialist wrote.