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Synthetic anabolic androgen (gonadotrophin inhibitor) Pregnancy: Contraindicated — virilisation of female fetus (clitoromegaly, labial fusion). Confirm negative pregnancy test before each cycle of treatment; effective non-hormonal contraception throughout.

Danazol

Brand names: Danol

Adult dose

Dose: Endometriosis: 200–800 mg/day in 2–4 divided doses for 3–6 months. Severe cyclical mastalgia (rare indication now): 100–400 mg/day. Hereditary angioedema (HAE) prophylaxis: 200 mg BD–TDS, titrate to lowest effective dose (often 50–200 mg/day).
Route: Oral
Frequency: BD–QDS
Max: 800 mg/day
Begin during menstruation to confirm absence of pregnancy. Use non-hormonal contraception throughout. Largely superseded by GnRH analogues for endometriosis and by C1-INH concentrate / lanadelumab for HAE.

Clinical pearls

  • Mechanism: pituitary suppression of LH/FSH + direct anti-oestrogenic and androgenic effects on endometrium → atrophy.
  • Voice changes (deepening) may be IRREVERSIBLE — counsel explicitly before starting; particular concern for women whose voice is professional.
  • Endometriosis: GnRH analogues (leuprorelin) with add-back HRT are now preferred — better tolerability and bone preservation.
  • Hereditary angioedema (HAE): once a mainstay of long-term prophylaxis. Now superseded by C1-esterase inhibitor concentrate (Berinert, Cinryze) and lanadelumab (subcutaneous monoclonal — FDA 2018).
  • Hepatic adenoma risk — recommended max 6-month course unless absolutely necessary; LFTs every 3 months.
  • Always non-hormonal contraception (barrier or copper IUD) — danazol does not reliably suppress ovulation and is severely teratogenic (virilisation of female fetus).

Contraindications

  • Pregnancy and breastfeeding (virilises female fetus)
  • Severe hepatic, renal, or cardiac impairment
  • Porphyria
  • Active thromboembolic disease or history of unprovoked VTE
  • Hormone-dependent malignancy
  • Undiagnosed vaginal bleeding
  • Children

Side effects

  • Androgenic: hirsutism, acne, deepening of voice (may be IRREVERSIBLE), weight gain, alopecia, libido changes
  • Anti-oestrogenic: hot flushes, vaginal dryness, breast atrophy
  • Menstrual disturbance: amenorrhoea (expected — therapeutic in endometriosis), irregular bleeding
  • Hepatotoxicity: cholestatic jaundice, hepatic adenoma (rare, usually with prolonged high-dose), rare hepatocellular carcinoma
  • Thromboembolism (rare)
  • Insulin resistance, hyperlipidaemia
  • Mood changes, depression
  • Pseudotumor cerebri (rare)
  • Photosensitivity

Interactions

  • Warfarin: ↑ INR markedly — reduce warfarin dose; monitor closely
  • Statins (especially simvastatin, lovastatin): ↑ rhabdomyolysis risk — avoid combination
  • Carbamazepine: ↑ carbamazepine levels — toxicity
  • Ciclosporin, tacrolimus: ↑ levels
  • Insulin / sulphonylureas: may need dose adjustment

Monitoring

  • LFTs at baseline, 3-monthly during treatment
  • Lipid profile annually
  • BP
  • Hepatic ultrasound if treatment >6 months (adenoma surveillance)

Reference: BNF 90; SmPC Danol; ESHRE Endometriosis Guideline 2022; HAE UK Consensus Document. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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