Cannabis-based medicines in multiple sclerosis--a review of clinical studies.

For some years a mixture of anecdotal report and data from animal models have implied a potential role for cannabis-based medicines in ameliorating a variety of symptoms of multiple sclerosis. Only recently however have large randomised controlled trials (RCTs) examined these potential effects rigorously. At present the results of RCTs have lacked a coherent message to the prescribing clinician and reasons for such heterogeneity in cannabinoid trials are discussed.