A research team led by Mark Ware, MBBS, MRCP, MS, at McGill University Health Centre (MUHC) in Montreal, has published results of a multicenter study of the safety of medical cannabis when used by patients with chronic noncancer pain. The study results, appearing online in The Journal of Pain, conclude that chronic pain patients who used cannabis daily for one year, when carefully monitored, had no increase in serious adverse events compared to pain patients who did not use cannabis. The authors assert that their work will serve as a benchmark study on cannabis side effects when used for pain management.
The study compared 215 patients with chronic noncancer pain who were either current or former users of medical cannabis to 216 controls—patients with chronic pain but who did not use cannabis—recruited from 7 clinics across Canada. The cannabis users received a quality-controlled, closely monitored dose of herbal cannabis (2.5 mg per day of product containing 12.5% THC). The researchers found no difference in risk of significant adverse effects between the groups. Based on the study findings, the researchers conclude that quality-controlled herbal cannabis, when used by cannabis-experienced patients as part of a monitored treatment program over one year, appears to have a reasonable safety profile, but that longer term monitoring for functional outcomes is needed. The study abstract, with link to the full journal article, may be read here.