Evidence doesn't support medical marijuana for rheumatological conditions such as arthritis, lupus or fibromyalgia, a review found. Instead, the dangers of cannabis use far outweigh any medical benefits that it may have.
Medical uses for marijuana are becoming more popular, with 20 U.S. states having legalized it for medical reasons. In Canada, where the study authors are based, "legal access to herbal cannabis is deemed a Charter Right when a 'medical need' has been demonstrated by the patient."
Authors reviewed the existing medical and legal landscape at Arthritis Care & Research.
One study cited by the authors found that 80% of marijuana users in a U.S. pain clinic treated myofascial pain with marijuana, and studies in the U.K. and Australia showed up to one-third of individuals report using marijuana to treat arthritis pain. In Canada, severe arthritis is the reason cited for two-thirds of medical marijuana uses.
"In many jurisdictions legislation is forcing physicians to accept medical responsibility for their patients who may be using herbal cannabis," the authors noted. "For example, in Canada, physicians will be required to provide a document equivalent to a prescription stipulating dosing, frequency and duration of use."
The main problems with medical marijuana include that tetrahydrocannabinol (THC) levels vary among plants up to 33% and absorption rates are between 2% and 56%, making the dosing of herbal cannabis unreliable. Smoking marijuana presents adverse effects on the respiratory system from hydrocarbons, tar and carbon monoxide. There are no studies of marijuana for rheumatic diseases, unlike for cancer and neuropathic pain. And, long-term use of cannabis may lead to mental illness, dependence, addiction, mental health and memory issues.
There is a mismatch between how much medical science knows about marijuana's efficacy and effects and growing public demand for medical and even recreational uses, the authors noted.
"Taking all factors into consideration, health care professionals should currently dissuade rheumatology patients from using herbal cannabis as a therapy," the authors concluded. "The evident mismatch between patients' needs and good medical practice may in part be politically driven with regulatory bodies acceding to public pressure."