Medical cannabis refers to the parts of the herb cannabis used as a form of medicine or herbal therapy, or to synthetic forms of specific cannabinoids such as THC as a form of medicine. The Cannabis plant has been used as a medicine over an extensive period of time.
Cannabis has been used for medicinal purposes for approximately 4,000 years. Writings from ancient India confirm that its psychoactive properties were recognized, and doctors used it for a variety of illnesses and ailments. These included a whole host of gastrointestinal disorders, insomnia, headaches and as a pain reliever frequently used in childbirth.
In the 1970s, a synthetic version of THC, the primary active ingredient in cannabis, was synthesized to make the drug Marinol.
Wherever the use of marijuana for medicinal purposes is legal, doctors tend to recommend it to treat chronic diseases and conditions. Examples of what medical marijuana is used for include AIDS, cancer, ADHD, multiple sclerosis, nausea resulting from chemotherapy, Crohn's disease, glaucoma, epilepsy, insomnia, migraines, arthritis and lack of appetite. Doctors have also used medical marijuana on terminally ill patients, as a way to alleviate some of their pain and improve their overall quality of life.
There's an extensive body of research that details marijuana's medicinal value. THC, a cannabinoid found in marijuana, has been shown to bind to the brain's endocannabinoid receptors. When this happens, the effects produced include a reduction in anxiety and pain, as well as a feeling of being high. Furthermore, research has shown cannabinoids to be successful at slowing the growth of certain types of cancer.
Cannabis contains approximately 60 different psychoactive chemicals called cannabinoids, of which the most important one is tetrahydrocannabinol (THC). The mode of action of THC is still not properly understood, although it is known that of the two stereoisomers (mirror images), the (-)-form (the left-handed form of the molecule) is 10-15 times more potent than the (+)-form.