Controversy surrounds the medical use of marijuana, with proponents saying it is useful for treating pain and the nausea and vomiting that are side effects of cancer chemotherapy and for restoring the appetite in people with AIDS. Its active ingredient, THC, was synthesized in 1966 and approved by the U.S. Food and Drug Administration in 1985; synthetic THC is available by prescription in pill form as dronabinol (Marinol) and nabilone (Cesamet). Proponents of medical marijuana say it is not as effective as the herb and is more expensive. In addition to THC, another cannibis derivative (or cannabinoid), cannabidiol (CDB), is an anti-inflammatory and antioxidant and also moderates THC's psychoactive effects.
A 1999 U.S.-government-sponsored study by the Institute of Medicine found that marijuana appeared beneficial for certain medical conditions, such as nausea caused by chemotherapy and wasting caused by AIDS. Because of the toxicity of marijuana smoke, however, it was hoped that further research might lead to development of new delivery systems, such as bronchial inhalers. A number of studies since 1999 have shown that smoked marijuana has pain-reducing effects when compared with marijuana stripped of its cannabinoids.
The Office of National Drug Control Policy has opposed legalization of the medical use of marijuana, citing law enforcement issues and the possibility that some would use it as a pretext to sell marijuana for nonmedical use, and the FDA said in 2006 that, despite the 1999 report, that marijuana "has no accepted or proven use in the United States." Proponents, disregarding the law, have set up networks for the distribution of the drug to people who they judge will be helped by it and continue to lobby for its legalization for medical use. In 1996 California enacted the first state law permitting the use of marijuana for medical reasons, and about one third of the states now have some sort of medical marijuana legislation. As a result of a Supreme Court ruling in 2005, however, these laws do not protect medical users with a prescription from federal prosecution. In 2009 Attorney General Eric Holder ordered that federal prosecutors not focus on persons who clearly comply with state medical marijuana laws, but federal law enforcement officials have moved to close many so-called marijuana dispensaries despite compliance, arguing in part that many prescriptions for marijuana are not justified medically. Another, lower court ruling permits doctors to discuss medical use of marijuana with their patients but forbids them to help patients obtain the drug. A number of countries, including Canada, permit the medicinal use of the drug.