A review of the existing scientific literature does not find enough evidence to back up marijuana use for treating rheumatic diseases.

Medicinal marijuana is not currently recommended for the treatment of pain resulting from rheumatoid arthritis or any rheumatic disease, according to a recent review published in Arthritis Care & Research.

Because of a lack of comprehensive study on the side effects of medical marijuana use and little regulation of dosage and consistency in product, the review by physicians and researchers at McGill University and the University of Michigan recommends against its use for the treatment of pain.

“There is currently no good study of the use of medical marijuana for the use of rheumatic diseases,” review co-author Dr. Mary-Ann Fitzcharles, a rheumatologist at Montreal General Hospital and the McGill University Health Centre’s Pain Centre, said. “Which means that we have no studies that will speak to the good or the negative, the efficacy or side effects either in the short or the long term.”

Along with Dr. Fitzcharles, Dr. Daniel Clauw, Peter Ste-Marie, and Dr. Yoram Shir, co-authored the review, and they are not alone in their assessment. The paper cites a study published in early 2013 that found that among family physicians in Colorado, only 19 percent thought that physicians should recommend medical cannabis and that 92 percent thought there should be more education.

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While it may not be time to entirely pack away the joints and cookies, there’s very little evidence backing up a full-on plunge into self-medication. Before medical marijuana can be used and prescribed like any other medication, there should be comprehensive study into how, how much, and for whom, the review says.

“There are many dimensions to its use. What we do know is that most people that are using herbal cannabis for medicinal purposes are accessing it illegally,” Fitzcharles said.

Rheumatic diseases encompass over 100 disorders that typically affect the joints, tendons, and bones and can be characterized by chronic pain and discomfort. Rheumatoid arthritis (RA), is an autoimmune disorder that causes the immune system to attack the membranes surrounding joints, causing pain and swelling.

Medical marijuana is currently not suited as a treatment for rheumatic diseases, both because of a lack of knowledge about the effects and the high associated with cannabis use, Dr. Fitzcharles says. Rheumatologists have many options for the treatment of RA and the intention when doing so is for there to be little impairment of day-to-day life.

“Our objective in pain management is to maintain function. We want our patients to be comfortable and feel good and get out and carry on with life,” Fitzcharles said. “Our great concern is the impact on function of person using herbal cannabis. There are clearly effects on cognitive function and psychomotive control which are of great concern.”

For older patients that are already unsteady on their feet, motor control impairment from herbal cannabis could result in a dangerous fall, she says. One main area where function and cannabis do not mix is in the car. “Do not operate a moving vehicle” rings true with any sort of substance use, and because independence in the western world is strongly associated with driving, mixing cannabis with cars isn’t recommended, and not just for RA patients, Dr. Fitzcharles says.

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Cannabis sativa—the substance up for debate—contains over 450 compounds, of which at least 70 are classified as phytocannabinoids and two are of medical interest. Tetrahydrocannabinol, or THC, is the psychoactive and pain-relieving substance which gives users the high.

On April 1, physicians in Canada will be allowed to prescribe marijuana essentially as another prescription, and in light of Health Canada regulation changes, further study should be required, Fitzcharles says.

Marijuana use is currently largely self-administered and accounts for a disproportionate amount of medical marijuana users. Previous studies have found that 80 percent of marijuana users in a U.S. pain clinic are there for myofascial pain, and in Canada, severe arthritis is the listed reason for 65 percent of medical marijuana use and possession.

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