More than half of Canadian multiple sclerosis (MS) patients are using medical cannabis to treat their symptoms, according to a new study published in the Multiple Sclerosis and Related Disorders journal.

Researchers from the University of Alberta Department of Medicine distributed anonymous questionnaires to MS patients in order to evaluate their usage of medical cannabis. “Our objective was to evaluate the prevalence of medical cannabis use by Canadians with MS, the reasons it is used, adverse effects, as well as the context surrounding how it is obtained and where users learned about it,” the study authors explained.

Out of the 344 patients who completed the survey, 215 (64.5%) said that they had tried medical marijuana at least once, and 180 (52.3%) said they were still using medical pot at the time of the study. Additionally, researchers found that patients who had been diagnosed with more severe or progressive forms of MS were more likely to have tried medical pot. And just over 76 percent of those who had used cannabis said that they had bought it from a legal, reliable source.

The vast majority of patients said that they used cannabis to help treat sleep problems (84%), pain (80%), and spasticity (68%). These results come as no surprise, given that dozens of clinical research studies have confirmed that cannabis can help treat chronic pain, inflammation, and sleep disorders. MS patients in most countries can receive prescriptions of Sativex, a blend of synthetic THC and CBD, to treat spasticity - even in the US, where nearly every form of cannabis remains federally prohibited.

Researchers also asked patients to report whether they experienced any negative side effects associated with their medical cannabis use. Just over half (57%) said that weed made them drowsy, 49% said they felt quiet or subdued, and around 28% reported that they had difficulty concentrating while they were stoned. No serious side effects were reported, however, and most patients found that the benefits of the medicine outweighed these minor side effects.

“This study showed that nearly two-thirds of survey respondents, comprised of Canadians living with MS, have tried medical cannabis at least once and that those with a greater disease burden were more likely to have tried it,” the researchers concluded. “Users reported that cannabis is moderately to highly effective in treating several symptoms and that adverse effects are not generally severe, nor are they the main factor driving medical cannabis cessation. Our results support the need for more research examining medical cannabis use in MS and for evidence-based resources to be publicly available for those exploring it as a potential therapy.”

This was the first study to explore Canadian MS patients' cannabis use over the past decade, but American researchers released a similar study in 2020. Researchers from the University of Michigan found that around 42% of MS patients said that they had used cannabis recently, and 90% of these users said that they chose to use weed for its medical benefits. About 44% of these patients also noted that they had found a specific blend of CBD and THC that worked best to treat their specific symptoms.