Evidence for Arthritis

Studies show it can be somewhat effective in treating pain from arthritis and related conditions. One meta-analysis of four randomized trials published as an abstract in the Annals of the Rheumatic Diseases, found that oral cannabinoids (cannabis oil) offered minimal to moderate improvement compared with placebo in individuals with musculoskeletal pain, including RA, back pain and fibromyalgia. Study author Janet Pope, MD, professor of medicine at the University of Western Ontario in Canada, notes that the results are not generalizable to smoking marijuana, and says, “The benefit was modest, and this was only studied for short periods of time.”

A 2011 British Journal of Clinical Pharmacology review examined 18 studies of smoked, oral and/or synthetic cannabis and concluded cannabis was safe and modestly effective in neuropathic pain (chronic pain that results from damaged or dysfunctional nerve fibers), and also had the potential to help treat RA and fibromyalgia pain. Additionally, cannabis has been shown to improve sleep – and a lack of sleep is known to exacerbate general pain and arthritis symptoms.

And cannabis holds promise for osteoarthritis (OA). “Joints have a complex endocannabinoid system and are able to produce their own endocannabinoids. But in disease states, such as with osteoarthritis, these endocannabinoids are broken down too quickly, so they can’t help with joint pain,” says Jason J. McDougall, PhD, associate professor in the departments of pharmacology and anesthesia at Dalhousie University in Halifax, Nova Scotia. In ongoing animal research, McDougall and his colleagues have found that by blocking certain enzymes or injecting cannabinoids into the joint, sensitivity and pain are reduced, leading McDougall to speculate that both endocannabinoid-targeting and cannabis-based treatments may hold new hope for individuals with OA.

Cannabis also may ease inflammation and affect immunity. In-vitro and animal studies have shown that both herbal and synthetic cannabinoids have the ability to suppress inflammation. Most recently, a Biological & Pharmaceutical Bulletin study in 2011 revealed that six different cannabinoids inhibited the activity of COX-2 enzymes, which play a role in arthritis-related inflammation. Other preliminary studies suggest cannabinoids may have immunosuppressive properties – including the ability to inhibit pro-inflammatory molecules called cytokines.

Why Docs Worry

Put simply, when you use herbal cannabis – that is, you inhale or ingest the marijuana plant in some form – you can’t be sure of what you’re getting. Cannabis contains hundreds of compounds, about 60 of them with cannabinoid properties. “But every plant contains different concentrations, so [using marijuana] is not the same as taking a carefully calibrated medication,” says Mary-Ann Fitzcharles, MD, associate professor of medicine in the department of rheumatology and pain management unit at McGill University in Montreal. She is considered one of the foremost experts on the use of cannabis in arthritis and fibromyalgia. In addition, she says, “There are no well-controlled studies on humans using herbal cannabis for arthritis. The few that exist are relatively small, and long-term effects are unknown.”

If you do obtain a prescription from a physician, you get your medication not at a pharmacy, but at a marijuana collective or dispensary – where the choices can be confusing at best, says Dr. Silverman. “You have a menu offering names like Blue Kush and Green Haze, which don’t necessarily tell you which kind of marijuana – indica, sativa or hybrid – it is. And not all list the potency – for example, 13 percent THC – or have been screened for fungus or pesticides. If you’re not familiar with marijuana, how do you know how much or which kind to use?”

Dr. Silverman says that most rheumatologists are not informed or prepared to give specific advice on how to use medical marijuana, “so you’re forced to rely on the advice of the person behind the dispensary counter,” he notes.