An androgenic hormone
Danazol
An androgenic hormone used for endometriosis, severe breast pain and hereditary angioedema, with masculinising effects.
What is Danazol?
Danazol is a man-made hormone with male-hormone-like (androgenic) effects that damps down the body's sex-hormone signals. It is used for endometriosis, severe breast pain and a condition called hereditary angioedema that causes attacks of swelling. Because of its androgenic effects it can cause masculinising changes such as deepening of the voice, acne and unwanted hair, and voice changes may be permanent. It needs reliable non-hormonal contraception during use and care in people with liver problems. The UK brand is Danol.
Education and reference only. This is a plain-language guide to Danazol — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Danazol is a synthetic hormone related to the male hormones (androgens). It works on the part of the brain that controls the ovaries and testes, reducing the body's production of sex hormones. It is used for endometriosis, where tissue like the womb lining grows outside the womb and causes pain; for severe breast pain and benign breast lumpiness when other measures have not helped; and for hereditary angioedema, an inherited condition that causes recurring attacks of swelling. Because newer, better-tolerated options exist for some of these, it is now used more selectively.
How it works
Danazol turns down the hormone signals from the brain (the pituitary gland) that drive the ovaries, lowering the levels of oestrogen the body makes. In endometriosis this starves the misplaced tissue of the hormone that feeds it, easing pain. In severe breast pain it reduces the hormonal stimulation of breast tissue. In hereditary angioedema it increases a protein in the blood (C1 esterase inhibitor) that is lacking, which reduces the frequency and severity of swelling attacks. Its androgenic, male-hormone-like activity is responsible for many of its side effects.
Company & origin
Originated / developed by: Generic (long-established).
An androgenic hormone used in the UK for endometriosis, severe breast pain and hereditary angioedema.
Practical use
How to take Danazol
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it as prescribed, usually with food, and complete the course you are given rather than stopping abruptly without advice.
- Use reliable non-hormonal contraception, such as condoms, throughout treatment, as it can harm a developing baby.
- Report any deepening of the voice promptly, as voice changes may be permanent.
- Attend for liver blood tests during treatment and report any yellowing of the skin or eyes.
- Tell your prescriber about acne, unwanted hair, swelling, severe headaches or visual changes.
Weighing it up
Advantages & disadvantages of Danazol
Advantages
- Can relieve the pain of endometriosis and reduce severe breast pain when other treatments have not helped.
- Reduces the frequency and severity of swelling attacks in hereditary angioedema.
- Taken as a capsule by mouth.
Disadvantages
- Causes masculinising effects such as acne, unwanted hair and voice deepening, which may be permanent.
- Cannot be used in pregnancy and needs reliable non-hormonal contraception throughout.
- Can affect the liver, raise the risk of blood clots and worsen cholesterol, so it is used cautiously.
Practical use
Good to know
The most important thing to understand about danazol is its androgenic effects. It can cause acne, oily skin, weight gain, unwanted hair growth and, importantly, deepening of the voice — and voice changes may not reverse even after stopping, so any voice change should be reported promptly. It can also cause irregular periods or stop them. Because it can harm a developing baby, reliable non-hormonal contraception (such as condoms or a non-hormonal coil) must be used throughout treatment, as it must not be taken in pregnancy. It can affect the liver, so liver blood tests are done and any yellowing of the skin or eyes should be reported. It may also raise the risk of blood clots, worsen cholesterol and, rarely, cause raised pressure in the head with headaches and visual changes. Because of these effects, treatment is kept as short and as low as is effective, and newer alternatives are often preferred where they exist.
Who should not take it / use with caution
- It must not be used in pregnancy or while breastfeeding, as it can harm the baby.
- It should not be used in people with significant liver, kidney or heart problems, or a history of blood clots.
- It is avoided in those with certain hormone-sensitive cancers or unexplained vaginal bleeding.
- It must be avoided by people with porphyria (an inherited condition affecting certain blood pigments), in whom it can trigger an attack.
Monitoring
- Liver blood tests during treatment and watching for yellowing of the skin or eyes.
- Watching for androgenic effects, especially voice changes, which may be permanent.
- Checking cholesterol and being alert to signs of blood clots or raised pressure in the head.
Side effects
- Masculinising effects such as acne, oily skin, unwanted hair and voice deepening (which may be permanent).
- Weight gain, fluid retention, irregular or absent periods, hot flushes and mood changes.
- Liver effects, raised cholesterol, a higher risk of blood clots and, rarely, raised pressure in the head.
Key interactions
- It can increase the effect of warfarin, so blood-clotting tests may need closer monitoring.
- It can raise the level of ciclosporin and tacrolimus, immune-suppressing medicines, increasing their effects.
- It can affect some diabetes medicines and statins, and caution is needed with other medicines that affect the liver.
Available as: Capsules taken by mouth.
Answers
Danazol: frequently asked questions
What is danazol used for?
It is used for endometriosis, severe breast pain and hereditary angioedema (a condition causing recurring attacks of swelling).
Can it change my voice?
Yes, because of its male-hormone-like effects it can deepen the voice, and this change may be permanent, so report any voice change promptly.
Do I need contraception while taking it?
Yes, you must use reliable non-hormonal contraception, such as condoms, throughout treatment, as it can harm a developing baby and must not be taken in pregnancy.
Why do I need liver blood tests?
Danazol can affect the liver, so liver tests are done during treatment, and you should report any yellowing of the skin or eyes.
Are there alternatives to danazol?
Yes, newer and often better-tolerated treatments exist for some of these conditions, so danazol is now used more selectively; your specialist can discuss the options.
Authoritative sources
- BNF
- NICE CKS
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