Key Points Question Are medicinal cannabinoids effective and well tolerated in the treatment of multiple sclerosis? Findings In this systematic review and meta-analysis of 17 randomized clinical trials including 3161 patients, cannabinoids were significantly associated with efficacy for subjective spasticity, pain, and bladder dysfunction compared with placebo. Cannabinoids had a higher risk of adverse events and withdrawals due to adverse events, with no statistically significant differences found for serious adverse events. Meaning Cannabinoids appear to be safe regarding serious adverse events, but their clinical benefit may be limited. Abstract Importance Cannabinoids have antispastic and analgesic effects; however, their role in the treatment of multiple sclerosis (MS) symptoms is...