Therapeutic Benefit of Smoked Cannabis in Randomized Placebo-Controlled Studies

The medicinal use of marijuana has been legalized in 28 states, with a wide range of specificity for approved medical conditions. Even with the emergence of non-combustion-based delivery systems, 90% of marijuana users in 2014 used smoked marijuana. This review summarizes the data available on the use of smoked marijuana for medical purposes. A literature search was performed to retrieve randomized controlled trials exploring the efficacy of smoked cannabis for treatment of a medical condition. Studies with the primary end point listed as the effect of smoked cannabis on a disease-specific characteristic were included. Open-label studies and studies using other administration methods were excluded. Seven studies met these criteria and were included in this review. Cannabis did not outperform placebo on experimentally evoked pain or the timed walk test. Clear evidence indicates that smoked cannabis reduces intraocular pressure, but the effect is too brief (less than 4 hrs) to be of therapeutic benefit for this chronic disorder. Consistent evidence also showed that smoked marijuana, even at lower concentrations of tetrahydrocannabinol, increased total daily calorie intake and number of eating occasions. Neither of the studies with quality of life as secondary outcome measures revealed statistically significantly improved outcomes with cannabis use.