Please use this link to access this publication. Abstract Study objective Little is known about the cause or optimal treatment of hyperemesis in habitual cannabis users. Anecdotal evidence supports the use of haloperidol over traditional antiemetics for this newly recognized disorder. We compare haloperidol with ondansetron for cannabis hyperemesis syndrome. Methods We randomized cannabis users with active emesis to either haloperidol (with a nested randomization to either 0.05 or 0.1 mg/kg) or ondansetron 8 mg intravenously in a triple-blind fashion. The primary outcome was the reduction from baseline in abdominal pain and nausea (each measured on a 10-cm visual analog scale) at 2 hours after treatment. Although the trial allowed for crossover, the primary...