Ancient civilizations recognized the practical uses for marijuana in medicine. When mixed with wine, it was used as an anesthetic. Cannabis was used for parasite hemorrhaging, nausea and vomiting, and for some infections. It was also given to women during childbirth. In fact, before aspirin was invented, marijuana was a primary pain reliever.

Only a few American states allow the use of marijuana for medical purposes today. There are some illnesses for which a doctor will recommend marijuana as an herbal medicine. A person using medical marijuana must have a prescription and is only allowed to have a small amount for medicinal purposes only. Marijuana is used to treat a variety of ailments. It is useful for treating stomach ailments. When smoked, marijuana reduces the intraocular pressure caused by glaucoma. Marijuana was also found to be useful in relieving intense pain from spinal cord injuries in Vietnam soldiers. As an appetite stimulant, marijuana has been used in treating HIV or other patients who are losing substantial amounts of weight because they cannot eat. Swallowing pills is often difficult for these patients. Marijuana has been helpful in treating patients undergoing chemotherapy who suffer from intense nausea. Crohn's Disease, bipolar disorder, and depression have been effectively treated with marijuana. It is also a bronchodilator for asthmatics and useful in treating constipation, epilepsy, and hypertension.

Researchers have found that marijuana can help treat autoimmune and inflammatory diseases as well as serving as a neuroprotectorant after a stroke. It is also believed to prevent neurons in Alzheimer's and Parkinson's patients. Treatment in patients with intense spasticity, hepatitis, and inflammatory bowel disease is promising. However, a lot of controversy remains about legalizing marijuana for medical reasons.