Medical cannabis (commonly referred to as "medical marijuana") refers to the use of the Cannabis plant as a physician-recommended drug or herbal therapy, as well as synthetic tetrahydrocannabinol (THC) and other cannabinoids. There are many studies regarding the use of cannabis in a medicinal context.[2][3] Use generally requires a prescription, and distribution is usually done within a framework defined by local laws. There are several methods for administration of dosage, including vaporizing or smoking dried buds, drinking or eating extracts, and taking synthetic THC pills.[4][5] The comparible efficacy of these methods was the subject of an investigative study by the National Institutes of Health.[3]

Medicinal use of cannabis is legal in a limited number of territories worldwide, including Canada, Austria, Germany, the Netherlands, Spain, Israel, Finland, and Portugal. In the United States, 13 states have recognized medical marijuana: Alaska, California, Colorado, Hawaii, Maine, Maryland, Michigan, Montana, Nevada, New Mexico, Oregon, Rhode Island, Vermont and Washington;[6][7] although California, Colorado, New Mexico and Rhode Island are currently the only states to utilize "dispensaries" to sell medical cannabis.