Danazol

Danazol is a synthetic hormone derived from ethisterone, a synthetic progesterone. Danazol works by suppressing the menstrual cycle to reduce oestrogen production and stop ovulation by a number of mechanisms that leads to altering normal endometrium and endometriosis tissue. It thins and becomes inactive, reduces or stops the normal period and any bleeding from the endometriotic cells. The endometriosis implants reduce in size and may completely resolve. It also has testosterone-like actions that may lead to side effects. Up to 80 per cent of patients have relief of mild to moderate endometriosis pain after two months of danazol²¹.

Due to the vast range of potential side effects of Danazol, it is not commonly used nowadays to treat endometriosis.

Possible side effects

Some of the side effects of Danazol may be due to its testosterone-like actions. The most common of these are:

• Weight gain
• Fluid retention
• Acne
• Oily skin and/or hair
• Bloating
• Decreased breast size
• Change in appetite
• Increased facial and/or body hair
• Increased muscle bulk
• Deepening of the voice
• Enlargement of the clitoris

Deepening of the voice, hair growth and enlargement of the clitoris are sometimes irreversible so if you notice any of these side effects contact your health practitioner immediately.

Some of the side effects are due to the low levels of oestrogen in the body. These side effects are commonly associated with menopause and include:

• Hot flushes / night sweats
• Vaginal dryness
• Headaches

Danazol can also cause a range of other side effects including:

• Vaginal bleeding
• Muscle cramps
• Nausea / vomiting
• Depression / mood swings
• Fatigue
• Decreased libido
• Decreased glucose tolerance
• Increased cholesterol levels
• Jaundice / liver disease

Gestrinone

Gestrinone is another hormonal steroidal tablet used to treat endometriosis. It is better tolerated than Danazol in many women and is not thought to have so many testosterone-like side effects. Gestrinone needs only to be taken twice weekly, which is another advantage.

Content updated 30 November 2011