.Diflucan is an antifungal antibiotic. Diflucan is used to treat infections caused by fungus, which can invade any part of the body including the mouth, throat, esophagus, lungs, bladder, genital area, and the blood. Diflucan is also used to prevent fungal infection in people with weak immune systems caused by cancer treatment, bone marrow transplant, or diseases such as AIDS. Diflucan may also be used for purposes other than those listed in this medication guide