Smoked cannabis has been shown to alleviate chronic neuropathic pain caused by trauma or surgery, according to the results of a new, small-scale study into the effects of the drug.

Researchers at McGill University Health Centre provided 21 participants aged 25 to 77 with cannabis of varying strengths. When inhaled in low doses three times a day, the stronger cannabis—containing 9.4% of the active ingredient THC—was shown to provide modest pain reduction, reduce anxiety and give users better sleep compared with individuals using lower-strength cannabis or placebo. The study period lasted five days.

This is among the first studies to determine the analgesic qualities of cannabis for treating chronic neuropathic pain, and the first to allow patients to smoke cannabis at home and monitor their reactions to the drug. The report appears in the latest edition of the Canadian Medical Association Journal.