Cannabis products with more THC slightly reduce pain but cause more side effects
Evidence review also finds products higher in CBD than THC have almost no benefit in reducing pain
A new systematic evidence review finds that cannabis products that carry relatively high levels of the psychoactive compound tetrahydrocannabinol, commonly known as THC, may provide short-term improvements in pain and function.
However, the review found THC-based products led to an increased risk of common adverse symptoms like dizziness, sedation and nausea.
At the same time, the review found that recent randomized controlled trials involving products mainly or only containing cannabidiol, or CBD, which does not have psychoactive properties, demonstrated almost no improvement in managing pain.
“This may be surprising to people,” said lead author Roger Chou, M.D., senior adviser for the Pacific Northwest Evidence-based Practice Center at Oregon Health & Science University. “Conventional wisdom was that CBD was promising because it doesn’t have euphoric effects like THC and it was thought to have medicinal properties. But, at least in our analysis, it didn’t have an effect on pain.”
The cannabis plant contains both THC and CBD. Both are believed to act on the body’s endocannabinoid system, which modulates pain. Many U.S. states, including Oregon, have legalized cannabis for both recreational and medicinal use, and many people have turned to cannabis to treat conditions including pain, anxiety and sleep.
The review, an update to a living review first published in 2022, was conducted by researchers at OHSU and published today in the Annals of Internal Medicine.
Researchers incorporated several additional short-term placebo-controlled randomized trials since the previous review. Both the original review and the new update found some evidence of pain relief for two prescribed products, dronabinol and nabilone, which are made of 100% THC or its analogue. Dronabinol and nabilone are FDA approved for treatment of nausea and vomiting due to chemotherapy, and one of them, dronabinol, is approved for HIV wasting syndrome.
The new review found that oral THC-only products slightly reduce pain severity.
Chou noted that the improvement in pain was relatively small — on the order of a half point to a point compared with a placebo on a 10-point pain scale.
“It’s complicated because cannabis products are complicated,” he said. “It’s not like taking a standardized dose of ibuprofen, for example. Cannabis is derived from a plant and has multiple chemicals in addition to THC and CBD that may have additional properties depending on where it’s grown, how it’s cultivated and ultimately prepared for sale.”
The medical profession is equally divided on the benefits of medicinal use of cannabis: The American College of Physicians recently declined to recommend inhaled cannabis for non-cancer pain whereas a previous expert panel issued a soft recommendation for people with chronic cancer or non-cancer pain when standard treatments did not work.
Chou said the review’s finding that CBD products failed to reduce pain will surprise many people.
“CBD-based products are widely available in dispensaries. Many people use these products and they think it helps,” he said. “Our goal is to provide some scientific basis to help people make their decisions.”
The researchers categorized cannabinoids by the ratio of THC to CBD (whether it was high, comparable or low); whether the product was synthetic (produced in a lab) or plant-based (as well as the degree of purification); and the administration method.
The data showed that oral THC-only products slightly reduced pain severity, but that across trials they were also linked to moderate-to-large increases in dizziness, sedation and nausea.
They concluded that more research is needed on long-term outcomes and other types of cannabis products; whether there are differences between THC-only products in effectiveness; and to better understand how results based on the products evaluated in the review apply to products that are available in dispensaries.
In addition to Chou, co-authors included Rongwei Fu, Ph.D., Azrah Y. Ahmed, B.A., and Benjamin J. Morasco, Ph.D.
The project was funded by the Agency for Healthcare Research and Quality of the U.S. Department of Health and Human Services, contract number 75Q80120D00006. Statements in the report should not be construed as endorsement by the AHRQ or the Department of Health and Human Services.
Journal
Annals of Internal Medicine
Method of Research
Systematic review
Subject of Research
People
Article Title
Cannabis-Based Products for Chronic Pain
Article Publication Date
22-Dec-2025
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
American College of Physicians
Below please find summaries of new articles that will be published in the next issue of Annals of Internal Medicine. The summaries are not intended to substitute for the full articles as a source of information. This information is under strict embargo and by taking it into possession, media representatives are committing to the terms of the embargo not only on their own behalf, but also on behalf of the organization they represent.
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1. 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
Abstract: https://www.acpjournals.org/doi/10.7326/ANNALS-25-03152
Editorial: https://www.acpjournals.org/doi/10.7326/ANNALS-25-04734
Summary for Patients: https://www.acpjournals.org/doi/10.7326/ANNALS-25-03152-PS
URL goes live when the embargo lifts
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.
Media contacts: For an embargoed PDF, please contact Gabby Macrina at gmacrina@acponline.org. To contact corresponding author Roger Chou, MD, please email chour@ohsu.edu.
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2. Once-weekly oral islatravir plus lenacapavir maintains high rates of virologic suppression in adults with HIV
Abstract: https://www.acpjournals.org/doi/10.7326/ANNALS-25-01939
URL goes live when the embargo lifts
A phase 2 randomized study evaluating the efficacy and safety of once-weekly oral islatravir plus lenacapavir (ISL+LEN) in virologically suppressed adults with HIV found that ISL+LEN maintained high rates of virologic suppression through 48 weeks, with no treatment-related grade 3 or greater adverse events or serious adverse events. These findings suggest that ISL+LEN may offer a promising long-acting oral regimen to address adherence challenges in HIV treatment. The study is published in Annals of Internal Medicine.
Researchers funded by Gilead Sciences evaluated the use of once-weekly ISL+LEN compared with daily oral bictegravir, emtricitabine, and tenofovir alafenamide combination (B/F/TAF) in persons with HIV-1 infection. Outcomes of interest included rates of virologic suppression through week 48 and adverse events. The open-label, active-controlled trial included 104 participants across 44 U.S. sites who had HIV-1 RNA viral load of less than 50 copies/mL while receiving daily B/F/TAF for at least 24 weeks. The participants were randomly assigned to receive either once-weekly ISL (2 mg) plus LEN (300 mg) or continue daily B/F/TAF for 48 weeks. The researchers found that at week 24, one ISL+LEN participant and none in the B/F/TAF group had HIV-1 RNA viral load of 50 copies/mL or more and almost all of the participants in both groups maintained HIV-1 RNA viral load of less than 50 copies/mL. At week 48, viral suppression rates were 94.2% for ISL+LEN and 92.3% for B/F/TAF, with no virologic rebound or emergent resistance detected. Treatment-related adverse events were mild in both groups. There were no discontinuations due to treatment-related adverse events, and changes in CD4+ T-cell and lymphocyte counts were not clinically meaningful. Adherence was high in both groups, with a greater proportion achieving at least 95% adherence in the ISL+LEN group. These results support further evaluation of ISL+LEN in phase 3 trials to assess safety and efficacy in a larger, global study population.
Media contacts: For an embargoed PDF, please contact Gabby Macrina at gmacrina@acponline.org. To contact corresponding author Amy E. Colson, MD please email Brian Plummer at brian.plummer@gilead.com.
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Also new this issue:
Advancing Physical Function Outcomes in Glucagon-Like Peptide-1 Receptor Agonist Trials
Jan H.M. Karregat, PhD; Stuart Phillips, PhD; Maria T.E. Hopman, PhD; Thijs M.H. Eijsvogels, PhD; and Tim Kambič, PhD
Ideas and Opinions
Abstract: https://www.acpjournals.org/doi/10.7326/ANNALS-25-03519
The Enemy
Michael Bretthauer, MD, PhD
Ideas and Opinions
Abstract: https://www.acpjournals.org/doi/10.7326/ANNALS-25-04873
Journal
Annals of Internal Medicine
Method of Research
News article
Subject of Research
People
Article Title
Cannabis-Based Products for Chronic Pain: An Updated Systematic Review
Article Publication Date
23-Dec-2025
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