Danazol
Synthetic derivative of ethisterone (ethinyl testosterone)
Also known as: Danocrine · Win-17757 · Anargil · Cyclomen · D-Zol · Danalem · Danazant · Danogen · Danokrin · Danol · Ectopal · Gonablok · Kendazol · Ladazol · Ladogal · Lisigon · Mastodanatrol · Norciden · Vabon · Winobanin · Zendol · Zoldan-A
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Adjunctive treatment of immune-mediated hemolytic anemia (non-regenerative forms) | 5 mg/kg PO three times daily. | PO | q8h | — | 🌎 NA |
| Adjunctive treatment of immune-mediated hemolytic anemia or thrombocytopenia | 5 mg/kg PO 2-3 times per day | PO | q8-12h | — | 🌎 NA |
| Adjunctive treatment of immune-mediated hemolytic anemia or thrombocytopenia | 10 mg/kg/day PO. Once anemia improves, corticosteroids may be slowly tapered and eventually DC'd. When remission maintained by danazol alone, may lower to 5 mg/kg/day. Slowly taper after 2-3 months of normal hemograms with frequent monitoring of hemograms. | PO | q24h | Long-term | 🌎 NA |
- Adjunctive treatment of immune-mediated hemolytic anemia (non-regenerative forms): Used to reduce the dose of glucocorticoids needed for long-term therapy.
- Adjunctive treatment of immune-mediated hemolytic anemia or thrombocytopenia: Rarely helpful. Costly and has limited effectiveness.
- Adjunctive treatment of immune-mediated hemolytic anemia or thrombocytopenia: Initially given in addition to prednis(ol)one.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Adjunctive treatment of immune-mediated hemolytic anemia | 5 mg/kg PO twice daily | PO | q12h | — | 🌎 NA |
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Danazol is a synthetic androgen derived from ethisterone. In veterinary medicine, it is primarily utilized as an adjunctive immunomodulatory agent for the treatment of immune-mediated hemolytic anemia (IMHA) and immune-mediated thrombocytopenia (ITP) in dogs and cats.
- Clinical Pearl: Due to its high cost, unpredictable efficacy, and slow onset of action, danazol is typically reserved as a salvage or third-line therapy when patients become refractory to standard immunosuppressants like glucocorticoids, cyclosporine, or mycophenolate.
- It exhibits synergism when combined with corticosteroids, potentially allowing for a reduction in the glucocorticoid dose once remission is achieved.
- In human medicine, it is also used for endometriosis, fibrocystic breast disease, and idiopathic thrombocytopenic purpura.
Mechanism of action
Danazol possesses weak androgenic, anabolic, and antiestrogenic properties. Its immunomodulatory effects are achieved through several mechanisms:
- Fc Receptor Modulation: Reduces the affinity of autoantibodies for the mononuclear phagocytic system Fc receptors → decreases the macrophage-mediated destruction of antibody-coated red blood cells and platelets.
- Steroid-Binding Globulin Competition: Competes with glucocorticoids for binding sites on corticosteroid-binding globulin (CBG) → increases the fraction of free, pharmacologically active glucocorticoids in circulation, enhancing their efficacy.
- Pituitary-Ovarian Axis Suppression: Inhibits the synthesis of sex steroids and binds directly to sex steroid receptors in target tissues.
Safety & warnings
Contraindications
- Pregnancy (Teratogenic - FDA Category X)
- Nursing/breastfeeding
- Severe cardiac function impairment
- Severe renal function impairment
- Severe hepatic function impairment
- Undiagnosed abnormal vaginal bleeding
Adverse effects
- Hepatotoxicity (rare but significant in dogs)
- Virilization in females
- Weight gain
- Lethargy
- Edema
- Testicular atrophy
- Hirsutism
- Alopecia
- Vaginitis (reported in humans)
Precautions
Warning: Danazol is highly teratogenic (FDA Category X) and must not be handled by pregnant women or used in pregnant animals.
- Use with extreme caution in patients with pre-existing hepatic, renal, or cardiac dysfunction.
- Laboratory Alterations: May alter thyroid panel results (decreased total T4, increased T3 uptake) without causing true hypothyroidism (free T4 and TSH remain normal).
- ALT (SGPT) and AST (SGOT) may increase early in therapy but typically decrease towards baseline later in therapy or after discontinuation.
Drug interactions
May significantly increase cyclosporine levels
By affecting carbohydrate metabolism, danazol may affect insulin requirements (doses may need to be increased) in diabetic patients
Concomitant use may enhance the anticoagulant effect as danazol may decrease the synthesis of procoagulant factors in the liver
Monitoring
- Efficacy (CBC, platelets, reticulocyte count)
- Hepatic function (baseline and at regular intervals while on therapy)
Pharmacokinetics
Absorption
Absorbed from the GI tract, but appears to be a rate-limited process (increasing the dosage does not yield a corresponding proportional increase in serum levels).
Distribution
Distribution information is practically nonexistent; the drug apparently crosses the placenta.
Metabolism
Believed to be principally metabolized in the liver.
Elimination
Limited veterinary data available.
Overdose
No specific information was located regarding acute toxicity in animals. Significant overdoses should initially be handled by contacting an animal poison control center and initiating gut emptying protocols (emesis or gastric lavage, followed by activated charcoal) when applicable.
Available products
Formulations
- Capsules
Human-labeled
- Danazol Capsules: 50 mg, 100 mg, & 200 mg
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Danazol capsules should be stored in well-closed containers at room temperature.
Client information
- Patience is key: It may take 2 to 3 months to see a positive response with this drug. Do not stop the medication abruptly unless instructed by your veterinarian.
- Monitor for liver issues: Watch for signs of liver toxicity such as yellowing of the eyes, skin, or gums (jaundice), loss of appetite, or vomiting.
- Watch for bleeding: Since this is often used for blood disorders, monitor for dark, tarry stools, unusual bruising, or bleeding gums.
- Handling precautions: Pregnant women should avoid handling this medication due to the risk of birth defects.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.