Cannabis-related products demonstrate short-term reduction in chronic pain

Summary: Cannabis products and synthetic medical cannabis may help relieve neuropathic pain, reports a new study.

Source: Oregon University of Science and Health

The evidence behind the effectiveness of cannabis-related products in treating chronic pain is surprisingly thin, according to a new systematic review of evidence by researchers at Oregon Health & Science University.

The federally funded review, which will be continually updated, was published today in Annals of Internal Medicine.

Researchers found evidence to support a short-term benefit in treating neuropathic pain – caused by damage to peripheral nerves, such as diabetic neuropathy resulting in pain described as burning and tingling, involving two FDA-approved synthetics with 100% tetrahydrocannabinol or THC : dronabinol (under the trade name Marinol) and nabilone (Cesamet). Both products also lead to notable side effects, including sedation and dizziness, according to the review.

Another product, a sublingual spray of equal parts THC and cannabidiol, or CBD, extracted from the cannabis plant known as nabiximols, has also shown evidence of some clinical benefit for neuropathic pain, although this product is not available in the US. to side effects such as nausea, sedation and dizziness.

“Overall, the limited amount of evidence surprised us all,” said lead author Marian S. McDonagh, Pharm.D., professor emeritus of medical informatics and clinical epidemiology at the OHSU School of Medicine.

“With so much buzz around cannabis-related products and the easy availability of recreational and medical marijuana in many states, consumers and patients can assume that there would be more evidence about benefits and side effects.

“Unfortunately, there is very little scientifically valid research on most of these products,” she said. “We’ve only seen a small group of observational cohort studies on cannabis products that would be readily available in states that allow it, and they weren’t designed to answer the important questions about treating chronic pain.”

Voters in Oregon, Washington and 20 other states have legalized medical and recreational marijuana, however, researchers have found that many of the products now available in US dispensaries have not been well studied.

“For some cannabis products, such as whole plant products, data are sparse with inaccurate effect estimates and studies have methodological limitations,” the authors write.

This situation makes it difficult to guide patients.

“Cannabis products vary widely in terms of chemical composition, and this can have important effects in terms of both benefit and harm to patients,” said co-author Roger Chou, MD, director of OHSU’s Pacific Northwest Evidence-based Practice Center. “This makes it difficult for patients and doctors alike, as the evidence for one cannabis-based product may not be the same for another.”

The effects of cannabis and related products are based on their ability to mimic the body’s own endocannabinoid system. The image is in the public domain

The live review, including an abstract visual summary of the findings, will also be shared in a new web-based tool launched by OHSU and VA Portland Health Care System earlier this year to help clinicians and researchers assess the latest evidence on effects. on marijuana health. Known as Systematically Testing the Evidence on Marijuana, or STEM, the project includes “clinical briefs” to help healthcare professionals translate the clinical implications.

“This new living evidence review is exactly the kind of resource clinicians need to clarify for patients the areas of potential promise, the cannabis formulations that have been studied and, most importantly, the key gaps in knowledge,” said co-author Devan. Kansagara, MD. , MCR, professor of medicine at the OHSU School of Medicine and staff physician at VA Portland.

The reviewers searched more than 3,000 studies in the scientific literature in January of this year and came up with a total of 25 with scientifically valid evidence – 18 randomized controlled trials and seven observational studies of at least four weeks.

The effects of cannabis and related products are based on their ability to mimic the body’s own endocannabinoid system. The system is made up of receptors and enzymes in the nervous system that regulate bodily functions and can affect the sensation of pain.

In the evidence review, researchers ranked product types into high, comparable, and low ratios of THC to CBD and compared their reported benefits and side effects.

Dronabinol and nabilone fit into the category of high THC to CBD ratio, with 100% THC (no CBD) showing the greatest benefit among the products studied, with meta-analysis of the six randomized controlled trials demonstrating statistically valid benefits for alleviating the neuropathic pain compared to a placebo.

“Honestly, the best advice is to talk to your primary care physician about possible treatments for chronic pain,” McDonagh said. “If you want to consider cannabis, you need to talk to your doctor.”

In addition to McDonagh, Chou, and Kansagara, co-authors included Benjamin J. Morasco, Ph.D., Jesse Wagner, MA, Azrah Y. Ahmed, BA, and Rongwei Fu, Ph.D.

About this research news in neuropharmacology and pain

Author: Press office
Source: Oregon University of Science and Health
Contact: Press Office – Oregon Health and Science University
Image: The image is in the public domain

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Original search: Closed access.
“Cannabis-based products for chronic pain. A Systematic Review” by Roger Chou et al. Annals of Internal Medicine


Cannabis-based products for chronic pain. A Systematic Review


Contemporary data on the utility of cannabinoids in chronic pain are needed.


Assess the benefits and harms of cannabinoids for chronic pain.

Data sources:

Ovid MEDLINE, PsycINFO, EMBASE, the Cochrane Library and Scopus until January 2022.

Study selection:

English, randomized, placebo-controlled trials and cohort studies (≥1 month duration) of cannabinoids for chronic pain.

Data extraction:

Data abstraction, risk of bias, and strength of evidence assessments were doubly reviewed. Cannabinoids were categorized by THC to CBD ratio (high, comparable or low) and source (synthetic, extracted or purified or whole plant).

Data Synthesis:

Eighteen randomized, placebo-controlled studies (no = 1740) and 7 cohort studies (no = 13,095) evaluated cannabinoids. The studies were mostly short-term (1 to 6 months); 56% enrolled neuropathic pain patients, with 3% to 89% female patients. Synthetic products with high ratios of THC to CBD (>98% THC) may be associated with a moderate improvement in pain severity and response (≥30% improvement) and an increased risk of sedation and are likely to be associated with a greatly increased risk of dizziness. Extracted products with high ratios of THC to CBD (range, 3:1 to 47:1) may be associated with a large increased risk of study withdrawal due to adverse events and dizziness. Sublingual spray with comparable THC/CBD ratio (1.1:1) is likely to be associated with a small improvement in pain severity and overall function and may be associated with a large increased risk of dizziness and sedation and a moderate increase in risk of nausea. Evidence for other products and outcomes, including long-term harm, was not reported or was insufficient.


Variation in interventions; lack of study details, including unclear availability in the United States; and inadequate evidence for some products.


Oral synthetic cannabis products with high THC to CBD ratios and sublingually extracted cannabis products with comparable THC to CBD ratios may be associated with short-term improvements in chronic pain and an increased risk of dizziness and sedation. Long-term outcome studies and further evaluation of the effects of the product formulation are needed.

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