Danazol

How it works

It suppresses the pituitary release of gonadotrophins and has weak androgenic effects, reducing ovarian hormone production and inducing an anovulatory, hypo-oestrogenic state.

Prescribing in practice

• It can cause androgenic adverse effects including weight gain, acne, hirsutism, and voice deepening, some of which may be irreversible, so women should be warned and treatment reviewed if virilisation occurs.
• It is contraindicated in pregnancy because of the risk of virilising a female fetus, and effective non-hormonal contraception must be used throughout treatment.
• Use with caution where there is hepatic impairment, cardiac or renal disease, or a history of thromboembolism, and avoid in undiagnosed abnormal genital bleeding.

Monitoring

Monitor liver function during treatment and watch for androgenic effects, weight gain, and signs of thromboembolism.

Counselling the patient

• Report any deepening of the voice promptly, as this change may not fully reverse.
• Use a reliable non-hormonal method of contraception, and stop the medicine and seek advice if you think you may be pregnant.
• Tell your doctor about any abdominal pain, jaundice, or unusual swelling.

Evidence & guidelines

Danazol is an established but second-line hormonal treatment for endometriosis, generally reserved for when better-tolerated options are unsuitable because of its androgenic adverse-effect profile.