8 months ago
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Evidence does not support the use of cannabidiol (CBD) products as a treatment for chronic pain, a new review found.
A meta-analysis of relevant studies published in scientific journals found a lack of convincing evidence that CBD – packaged as oils, vapes, creams, gummies, drinks, and more – reduces pain, prompting the team of UK and Canadian researchers to advise caution when comparing the marketing claims of CBD products.
Scientists were still learning about the potential benefits and risks of CBD when its promotion as a pain reliever took off with a substantial head start.
The authors hope more balanced, evidence-based advice can now be given to patients and their care providers, while research focuses on effective pain treatments.
"Untreated chronic pain is known to seriously damage quality of life, and many people live with pain every day," says senior author Chris Eccleston, a pain scientist at the University of Bath.
"Pain deserves investment in serious science to find serious solutions."
The International Association for the Study of Pain (IASP) issued a position statement in 2021 stating there was insufficient evidence from high-quality research to support the general use of cannabinoids to treat pain. While animal studies suggested potential pain relief mechanisms, human trials were lacking.
"This is not a door closing on the topic," an IASP summary said at the time, "but rather a call for more rigorous and robust research … and to ensure the safety of patients and the public through regulatory standards and safeguards."
Despite this, CBD products are widely advertised in stores and online as a therapy for pain relief. Their claims fuel a burgeoning market expected to exceed US$60 billion by 2030.
"CBD presents consumers with a big problem," says Eccleston. "It's almost as if chronic pain patients don't matter, and that we're happy for people to trade on hope and despair."
Eccleston and team looked at 16 clinical trials conducted between 2020 and 2023 which tested various CBD products for several painful conditions. Involving a total of 917 participants, the tests included doses between 6 and 1,600 milligrams administered orally, under the tongue, or topically, for courses of up to 12 weeks.
Across the 16 studies testing pharmaceutical-grade CBD, 15 found CBD didn't relieve pain any better than a placebo. Only one small trial of 19 patients with thumb arthritis noticed a significant reduction in their pain using topical CBD compared to a control.
The researchers also caution that CBD products sold directly to the public can have different amounts of CBD than claimed on the label, and contain other cannabis ingredients or synthetic chemicals that haven't been tested for safety.
A 2022 study found only a quarter of the 105 products tested were accurately labeled for CBD, with some containing more CBD than claimed, and others less.
In addition to CBD, 35 percent of these products contained tetrahydrocannabinol (THC), the main psychoactive ingredient in cannabis, including some that claimed to be THC-free.
The authors say it's understandable that people turn to CBD products for pain relief. Chronic pain affected an estimated 1 in 5 US adults in 2021, and is the most common chronic condition in the UK.
"For too many people with chronic pain, there's no medicine that manages their pain," explains first author Andrew Moore, a pain scientist from the University of Oxford.
"Chronic pain can be awful, so people are very motivated to find pain relief by any means. This makes them vulnerable to the wild promises made about CBD."
The FDA announced in January 2023 that CBD needs a new regulatory framework as the existing framework does not manage the risks, such as clear labels to prevent contaminants, limits on CBD content, and ways to mitigate the risk of children ingesting the products. For now, the FDA monitors claims made about CBD products and regularly issues warnings on lack of efficacy.
"There should be no excuses for misleading the public," the team writes. However, it's unclear if penalties can be enforced against those who do, and they suggest there's a long way to go when it comes to regulating the sale of CBD products.
"What this means is that there are no consumer protections," says Moore. "And without a countervailing body to keep the CBD sellers in check, it's unlikely that the false promises being made about the analgesic effects of CBD will slow down in the years ahead."
The study has been published in The Journal of Pain.
