Danazol (DA-na-zole) may be used for a number of different medical problems. These include treatment of pain and/or infertility due to endometriosis, a tendency for females to develop cysts in the breasts (fibrocystic breast disease); or hereditary angioedema, which causes swelling of the face, arms, legs, throat, windpipe, bowels, or sexual organs. Danazol may also be used for other conditions as determined by your doctor.