The Cannabis plant has a history of medicinal use dating back thousands of years across many cultures.
A Cannabis plant includes more than 400 different chemicals, of which about 70 are cannabinoids. In comparison, typical government-approved medications contain only 1 or 2 chemicals. The number of active chemicals in cannabis is one reason why treatment with cannabis is difficult to classify and study.
Medical cannabis has several potential beneficial effects. Evidence is moderate that it helps in chronic pain and muscle spasms. Low quality evidence suggests its use for reducing nausea during chemotherapy, improving appetite in HIV/AIDS, improving sleep, and improving tics in Tourette syndrome.
When usual treatments are ineffective, cannabinoids have also been recommended for anorexia, arthritis, migraine, and glaucoma.
The combination of Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) extracts give subjective relief of spasticity, and evidence also suggests that oral cannabis extract is effective for reducing patient-centered measures of spasticity.