Injection drug users constitute the second largest subset of the U.S. population at risk for HIV infection and AIDS-associated mortality. Narcotic addiction is often treated by use of methadone. Fluconazole has been shown to be highly effective in treating symptomatic mucosal candidiasis, but it is unknown whether fluconazole affects methadone metabolism, which could result in symptoms of methadone withdrawal or overdose in patients taking the drugs in combination.