How physicians should respond to the new cannabis regulations

The new Health Canada regulations on medical marihuana would allow patients to purchase dried cannabis from a licensed distributer with a medical prescription. Yet available evidence does not support the safety and efficacy of smoked cannabis as an analgesic. The controlled trials on smoked cannabis were very brief and had small sample sizes. The subjects had severe neuropathic pain syndromes, whereas most medical marihuana users have fibromyalgia, low back pain and other conditions commonly seen in primary care. None of these trials compared smoked cannabis to oral cannabinoids, which may be as or more effective than smoked cannabis for chronic pain. Oral cannabinoids are also far safer than smoked cannabis, which produces very high plasma THC levels, and toxic chemicals that are carcinogenic and atherogenic. In addition, studies show that the population that uses medical marihuana for chronic pain is at higher risk for cannabis-related harms. Compared to pain patients in primary care, medical cannabis users are more likely to be younger, male, and to have a history of addiction or mental illness. This puts them at high risk for cannabis related harms such as addiction, psychosis, depression, poor school and work performance, and motor vehicle accidents. It is unsafe to prescribe cannabis to such patients, and also often unnecessary, since the majority of medical cannabis users have benign pain conditions for which numerous effective and safe treatments are available. We propose that, for patients who are at low risk of harms from smoked cannabis, physicians sign a declaration rather than a prescription. A cannabis prescription endorses the therapeutic use of a substance which lacks medical evidence of benefit, and is much less safe than existing treatments. In contrast, a declaration affirms that the physician does not oppose, on medical grounds, the patient's decision to use a substance from which he or she at low risk of harm. Thus, a declaration maintains honesty and integrity in our interactions with our patients, directs physicians' attention towards assessment and intervention for cannabis-related harms, and encourages patients and physicians to consider other treatments, ones with proven benefit.