Danazol is a man-made form of a steroid and is similar to the hormone testosterone. This medication is commonly prescribed for women with pelvic pain and infertility associated with endometriosis, a painful condition in which the lining of the uterus known as the endometrium grows outside the uterus. Other indications for danazol treatment include fibrocystic breast disease (benign breast lumps) and hereditary angioedema (inflammation of airway, face, arms, and legs).
How does Danazol Work?
Danazol exerts its beneficial effects through its anti-estrogenic and anti-progestogenic activities. This medication reduces the production of the hormones estrogen and progesterone by suppressing certain receptors in the endometrium, resulting in thinning of the lining of the uterus. Danazol also causes marked suppression of sex hormone binding globulin (SHBG) levels in the blood, which in turn increases free testosterone. This ultimately results in androgenic effects such as increase in muscle mass and fat loss.
Overall Health Benefits of Danazol
- Increases pregnancy rate [1-16]
- Combats cancer [17-33]
- Boosts immune function [34-50]
- Improves cardiovascular health [51-55]
- Improves body composition [56-57]
Increases Pregnancy Rate
An overwhelming body of high quality studies shows that danazol can be a safe and effective therapeutic option in women with endometriosis and infertility:
- In patients with unsuccessful in vitro fertilization-embryo transfer, danazol treatment (400 mg/d orally for 12 weeks) showed a significant increase in pregnancy rate. 
- Danazol treatment at 100mg daily for 3 months is associated with 40 to 50% pregnancy rate in women with endometriosis. 
- Danazol administration also improved pregnancy outcomes in women with endometriosis who had surgical procedure and those who had non-invasive laser treatment. [3-4]
- Danazol administration in women with endometriosis for 3-6 months is associated with regression and disappearance of endometriosis and higher pregnancy rate. 
- A 6-year study assessing the benefits of danazol in infertile women found a higher pregnancy rate for the 800-mg danazol regimen than for the 400-mg regimen. 
- In women with endometriosis-associated infertility, danazol treatment is associated with 45% pregnancy rate compared to 32% with lynestrenol (a fertility medication). 
- A study also found that danazol is as effective as gestrinone (drug used for endometriosis) in the treatment of infertility. 
- A 3-year study on infertile women found that danazol therapy improved ovulation with minimal side effects. 
- Postoperative danazol therapy in infertile patients with severe endometriosis is associated with higher pregnancy rate. 
- Vaginally administered danazol has been found to improve heavy menstrual bleeding and restore fertility in women with endometriosis. 
- A trial of 100 mg danazol daily for 3 months in infertile women found that the treatment increased pregnancy rate by 40-50%. 
- In patients with stage 1 endometriosis, treatment with danazol for 6 months resulted in more pregnancies. 
- In patients with mild or moderate endometriosis who had no previous treatments, administration of danazol increased pregnancy rate. 
- In patients with severe endometriosis, danazol treatment administration following surgery significantly improved pregnancy rate. 
- In patients with endometriosis, vaginal administration of danazol improved heavy menstrual bleeding and restored fertility. 
Evidence also suggests that danazol can help treat various types of malignant cells because of its potent anti-cancer properties:
- In premenopausal and postmenopausal patients with advanced breast cancer, danazol treatment for periods ranging between 3 days and 30 months resulted in stabilization of the disease. 
- In patients with metastatic breast cancer, danazol treatment at a dose of 200 mg three times daily significantly improved symptoms. 
- In patients with advanced breast cancer, danazol is associated with better treatment outcomes. 
- In breast cancer cells, danazol treatment induced cell cycle dysregulation and programmed cell death (apoptosis). 
- In patients with advanced breast cancer, danazol administration improved survival rate. [21-22]
- In a human endometrial cancer cell line, danazol displayed growth-inhibitory effect. [23-24]
- In women with benign breast disease, danazol treatment reduced the risk of cancer progression. 
- In menopausal and postmenopausal women with uterine tumor, danazol decreased tumor size without further recurrence and/or progression of the disease. [26-27]
- In women with metastatic breast cancer, danazol has been found to be more effective than other chemotherapeutic drugs such as tamoxifen and fluoxymesterone. 
- A study also found that danazol can induce cell cycle arrest of multi-drug resistant cancer cells. 
- A cell study found that monotherapy with danazol induced apoptosis and cytotoxicity of leukemic cells. 
- A cell study found that danazol increased the sensitivity of cancer cells to chemotherapeutic drugs. 
- A cell study also found that danazol was toxic to human cervical cancer cells. 
- In patients with advanced breast cancer, danazol treatment stabilized the disease. 
Boosts Immune Function
Aside from its potent anti-cancer properties, numerous studies suggest that danazol has immune-modulating properties that can help ward off a wide array of diseases:
- In patients with thrombocytopenia (low platelet count), danazol therapy increased the production of the immune system cell T lymphocytes. 
- A 2013 study published in the Iranian Journal of Basic Medical Sciences found that danazol can treat human T-cell lymphotropic virus type I, an infection that can progress to leukemia. 
- In patients with primary immune thrombocytopenia, low-to-medium dosage of danazol is better tolerated and resulted in long-term disease remission. 
- In patients with immune thrombocytopenic purpura, a blood clotting disorder, danazol treatment increased the production of white blood cells and reduced the number of abnormal platelets. [37-38]
- In patients with angio-immunoblastic lymphadenopathy, a cancer of the blood and lymph nodes caused by impaired immune function, danazol treatment showed immune-boosting properties. 
- In an animal model of immune-mediated anemia, danazol treatment reduced the binding of immuno-globulin to the red blood cell’s surface, thus preventing the formation of abnormal RBCs. 
- In older women with autoimmune hemolytic anemia, danazol modified cell membranes which in turn led to specific immune modulations. 
- In patients with hereditary angioedema, danazol exerts its therapeutic effect via promotion of C4 synthesis and increasing C1 esterase inhibitor production. 
- In patients with IgA nephropathy, a kidney disease characterized by build-up of the antibody immunoglobulin A (IgA) in the kidneys, danazol administration stabilized the disease. 
- In rats, danazol administration at a dose of 100 mg/kg per day ameliorated the endometrial implant-induced alterations of the immune system. 
- In a mouse model of lupus, a long-term autoimmune disease, danazol administration at an oral dose of 100 mg/kg, significantly prolonged survival. 
- In patients with aplastic anemia (inadequate production of blood cells), danazol therapy improved survival rate and increased T regulatory cells. [46-47]
- In patients with uterine problems, danazol treatment prevented the formation of antibodies that attack the immune system. [48-49]
- In patients with bleeding problems, danazol treatment increased platelet count. 
Improves Cardiovascular Health
A growing body of evidence also found that danazol is good for the heart and can be beneficial in people with cardiovascular disease:
- In patients with recurrent painful ulcers of the lower extremities, low-dose danazol reduced cardiovascular risk factor by decreasing the levels of lipoprotein a. 
- In healthy volunteers and patients with hereditary angioedema, danazol administration improved dilation of heart blood vessels. 
- In mice, injection of danazol induced prolonged cell survival of transplanted hearts. 
- In normal women, danazol treatment reduced the risk of atherosclerosis (plaque build-up within the heart). 
- In patients undergoing dialysis, danazol administration has been found to treat blood clots. 
Improves Body Composition
By suppressing sex hormone binding globulin (SHBG), danazol boosts the production of the primary male hormone testosterone. Numerous high quality studies show that this mechanism promotes fat loss and increased production of lean muscle mass:
- In premenopausal women undergoing danazol treatment for endometriosis, a significant reduction in body fat and increase in lean tissue mass were observed after 6 months. 
- In patients with endometriosis, danazol treatment resulted in fat reduction of the legs. 
- Tei C, Miyazaki T, Kuji N, Tanaka M, Sueoka K, Yoshimura Y. Effect of danazol on the pregnancy rate in patients with unsuccessful in vitro fertilization-embryo transfer. J Reprod Med. 1998;43(6):541-6.
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- Soong YK, Chang FH, Chou HH, et al. Life table analysis of pregnancy rates in women with moderate or severe endometriosis comparing danazol therapy after carbon dioxide laser laparoscopy plus electrocoagulation or laparotomy plus electrocoagulation versus danazol therapy only. J Am Assoc Gynecol Laparosc. 1997;4(2):225-30.
- Chatterjee S, Dey S, Chowdhury RG, Ganguly DD. Pregnancy outcome in pre-operative danazol treatment followed by laparoscopic correction in infertility associated with endometriosis. J Indian Med Assoc. 2012;110(10):694-9.
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