Side Effects--Cardiovascular/Endocrine

• In some instances, states drugs.com, danazol has been connected with increased blood pressure and heart failure. Endocrine side effects include the "inhibition of estrogen synthesis," which results in flushing, vaginal dryness and pain, and reduction in breast size. Spermatogenesis may also be prevented when large does of danazol are given to patients. If any of these symptoms are experienced, seek immediate medical attention.
  
  

Side Effects--Gastrointestinal/Genitourinary

• Gastrointestinal side effects according to include nausea, vomiting, constipation and rarely pancreatitis. These can be severe and your physician should be contacted if they persist. In men, drugs.com states that "genitourinary side effects have included oligospermia and decreased ejaculatory volume." In older male patients, there have been cases of enlarged prostate that have lead to urinary tract problems such as blockage. In women, danazol may deepen the voice, cause acne and cause complications with the menstrual cycle. If virilization occurs, contact your doctor.
  
  

Side Effects--Hematologic/Metabolic

• Hematologic side effects have included "thromboembolic and thrombophlebotic events (including sagittal sinus thrombosis)," which have been connected to increased red blood cell count and strokes, states drugs.com. Danazol has also been linked to complications with cholesterol levels within the body. Drugs.com explains that it can increase the level of low-density lipoproteins, which are "bad" cholesterol, and decrease the level of high-density lipoproteins, which are "good" cholesterol. Decreased glucose tolerance has also occurred.
  
  

Other Side Effects

• Other mild and severe side effects include muscle cramps or spasms and pain, swelling or pain in the joints, neck, back, or extremity pain, and "rarely carpal tunnel syndrome which may be secondary to fluid retention," according to drugs. com. Rashes may appear on the skin and the skin may also be sensitive to sunlight. Further side effects include Stevens-Johnson syndrome, increased insulin requirements in diabetic patients, change in sexual desires, vision problems, bleeding gums, fever, pelvic pain and nipple discharge.
  
  

Allergic Reactions

• Immediately contact your doctor is you experience an allergic reaction to danazol. Symptoms of an allergic reaction are swelling of the tongue, face, throat, lips and mouth. Other serious side effects include chest pain, tightness of the chest, difficulty breathing, fainting, yellowing of the skin, persistent vomiting and pains of the legs and arms.