Abstract Objective To compare the analgesic efficacy and side effects of the synthetic cannabinoid nabilone with those of the weak opioid dihydrocodeine for chronic neuropathic pain. Design Randomised, double blind, crossover trial of 14 weeks’ duration comparing dihydrocodeine and nabilone. Setting Outpatient units of three hospitals in the United Kingdom. Participants 96 patients with chronic neuropathic pain, aged 23-84 years. Main outcome measures The primary outcome was difference between nabilone and dihydrocodeine in pain, as measured by the mean visual analogue score computed over the last 2 weeks of each treatment period. Secondary outcomes were changes in mood, quality of life, sleep, and psychometric function. Side effects were measured...