The therapeutic use of cannabis (marijuana) is a hot topic in some parts of the United States. The National Institutes of Health do not recommend its use for treatment of any illness, though some physicians prescribe it for pain, glaucoma, nausea and anorexia associated with chemotherapy, and, less commonly, for epilepsy, multiple sclerosis, migraine, and asthma. Laws on medical usage vary by state, with 13 states, as of July 2009, permitting medical usage under certain conditions. The majority of Web sites on medical marijuana have a bias one way or another. Updated February 2010