There are seemingly endless claims that marijuana has medicinal properties, but many still doubt these benefits due to the fact they believe medical marijuana lacks substantial clinical and scientific research. While it is true that marijuana's schedule I status in the United States creates difficult hurdles for researchers who want to study medical marijuana, there is still extensive research supporting claims to its therapeutic properties. According to a new literature review published in the journal Critical Reviews in Plant Sciences, a pair of German researchers have identified 140 clinical trials since the year 1975 that involved around 8,000 participants and looked into the safety and efficacy of cannabis or its cannabinoids.
Most of the literature involving cannabis or cannabinoids was geared towards the treatment of chronic or neuropathic pain, and authors found 35 controlled studies involving 2,046 patients that used cannabis or cannabinoids for pain management. The National Academy of Sciences acknowledged the existence of "conclusive or substantial evidence" behind the efficacy of cannabis for chronic pain relief. Many studies have also assessed cannabinoids as anti-emetic agents or appetite stimulants, and the researchers found 43 trials involving 2,498 patients looking into these benefits. There were also 14 trials looking into cannabis or cannabis extracts for the treatment of multiple sclerosis. Additionally, the researchers discovered several trials evaluating cannabis for Crohn's disease, Tourette's syndrome, Parkinson's disease, glaucoma, epilepsy, and other indication.