Cannabinoids for Treatment of MS Symptoms: State of the Evidence

Cannabis and cannabinoids have been used medically and recreationally for thousands of years and recently there has been a growing body of research in this area. With increased access now that medical marijuana is available in many jurisdictions, patients and providers want to know more about the evidence for benefits and risks of cannabinoid use. This paper provides an overview of the available cannabinoid-based formulations, a summary of the highest quality evidence for the use of cannabinoids for treating spasticity and pain associated with multiple sclerosis (MS), and a discussion of possible dosing regimens based on information from these studies.

Two recent high-quality systematic reviews concluded that the only strong evidence for medical marijuana in neurological disorders was for reducing the symptoms of patient-reported spasticity and central pain in MS and that the only complementary and alternative medicine (CAM) intervention in MS with strong supportive evidence was cannabinoids. Based on this review, they concluded that nabiximols (Sativex oral spray), oral cannabis extract (OCE), and synthetic tetrahydrocannabinol (THC) are probably effective at reducing patient-reported symptoms of spasticity in people with MS, but OCE and synthetic THC were not found to be effective for reducing physician-administered measures of spasticity. In addition, nabiximols, OCE, and synthetic THC are probably effective at reducing MS-related pain. Cannabinoids were generally well-tolerated. However, cannabis use has been associated with an increased risk of psychosis and schizophrenia in at-risk individuals, there is growing evidence that cannabis can increase the risk for cardiovascular diseases, including myocardial infarction (MI), hypertension, heart failure, and stroke, and a recently recognized adverse effect of cannabis is cannabinoid hyperemesis syndrome. The medical use of cannabinoids remains controversial. While cannabinoids have been studied for a variety of neurologic disorders, there is strongest evidence to indicate benefits in treatment of spasticity and neuropathic pain in multiple sclerosis. Although the best dose for an individual remains uncertain, most participants in the studies discussed in this paper used between 20 and 40 mg of THC a day in divided doses. Adverse events in studies were generally more common in the groups using cannabinoid products but serious adverse events were rare and cannabis products were generally well-tolerated. Cannabis use does appear to be associated with increased risk of certain adverse events, including psychosis, cardiovascular diseases, and cannabinoid hyperemesis syndrome.