“Joints for Joints.” That was the title of a lighthearted yet science-based debate at the annual scientific meeting of the American College of Rheumatology/Association of Rheumatology Health Professionals in 2011. The topic: whether medical marijuana – that is, the medicinal use of the cannabis plant – was a safe and effective arthritis treatment.

Taking the “con” view, Stuart L. Silverman, MD, attending physician at Cedars-Sinai Medical Center in Beverly Hills, Calif., argued that although some cannabis research was compelling, inconsistent dosing and quality-control issues, as well as a lack of well-controlled research, meant marijuana was not “ready for prime time,” particularly where arthritis was concerned.

Taking the “pro” position, Arthur Kavanaugh, MD, a professor of medicine at the University of California, San Diego (who declined to be interviewed for this article), argued that the type of carefully controlled trials Dr. Silverman called for had not been conducted on aspirin, either, and that cannabis – used medicinally for nearly 5,000 years – had few side effects, eased pain from rheumatoid arthritis (RA), and might reduce inflammation as well.

Drs. Silverman and Kavanaugh didn’t reach any firm conclusions, but after multiple rheumatologists in the audience revealed that many of their patients were inquiring about or already using cannabis, one thing was clear: Medical marijuana had gone mainstream. Yet many in the medical establishment have strong concerns.

Currently, 20 states and Washington, D.C., have legalized limited use of medical marijuana for certain conditions, and nine more states may follow suit. (Some, including California, permit it for arthritis; others, such as New Jersey, do not.) Two states, Washington and Colorado, have decriminalized even its recreational use. A 2011 Journal of Pain survey revealed that almost 10 percent of Americans with chronic pain use marijuana. Although it’s unclear how many of those have arthritis, large-scale surveys from the United Kingdom and Australia indicate that roughly one-third of people who use medical marijuana do so for arthritis – and most report considerable pain relief. Additionally, a Canadian study in Arthritis Care & Research found that among 457 patients with fibromyalgia, 13 percent used cannabis to manage their disease.  

How It Works

Research shows that, among other things, cannabis eases chemotherapy-induced nausea and loss of appetite, and relieves spasms in individuals with multiple sclerosis. Even so, pain relief is perhaps the most well-recognized and studied effect.

Several decades ago, scientists discovered that mammals, including humans, have a pain-regulating system (the endocannabinoid system) with receptors in nervous system tissue, immune cells and bone and joint tissue. These receptors respond to cannabinoids, a set of compounds that include endocannabinoids, which the body creates on its own; and phyto-cannabinoids, plant-based compounds found in marijuana that are very similar to endocannabinoids.

The best known cannabinoids are THC (delta-9-tetrahydrocannabinol, the psychoactive compound in cannabis) and CBD (cannabidiol, a major constituent of the plant thought to act as a sedative and reduce inflammation, nausea and convulsions). They have complex mechanisms, but in a nutshell, cannabinoids can reduce pain by acting on certain receptors.

Of the two main cannabis species – sativa and indica – sativa contains higher THC and lower CBD levels and produces a more euphoric “high.” Indica has higher CBD and lower THC levels and is used to aid sleep and ease pain.

Cannabinoids also seem to have a positive impact on some other pain medications. One study, in Clinical Pharmacology & Therapeutics in 2011, found that chronic pain patients using long-acting oxycodone or long-acting morphine who inhaled vaporized herbal cannabis experienced a significant decrease in pain – far more than with the opioids alone. Though the study was of just 21 patients, study author Donald I. Abrams, MD, professor of clinical medicine at the University of California, San Francisco, says it “suggests that cannabis has the potential to relieve pain and decrease use of opioids, which, unlike cannabis, are associated with major side effects.”