Medical Marijuana Marijuana is derived from the Cannabis plant. It is believed that Marijuana has been used as a medicine for hundreds of years. It is known though that, before the introduction of Aspirin, Cannabis, as a reliever of pain was the most commonly used product. More recently marijuana has been shown to be a very versatile form of medicine. It can assist chemotherapy patients in stopping vomiting. It can give sufferers of anorexia an appetite. It is effective as a pain reliever and ...