Hormonal treatments are used to act on the endometriosis and stop its growth. They either put the woman into a state of pseudo-pregnancy or pseudo-menopause. (Pseudo means simulated or artificial – both states are reversed when the patient has stopped taking the hormones.)
In addition, testosterone derivatives are occasionally used to mimic the male hormonal state; these drugs are generally synthetic hormones. While not all of the hormonal drugs used to treat endometriosis are licensed as a contraceptive, they all have a contraceptive effect, so are not used if the patient is trying to conceive. Please note: only the oral contraceptive pill and the Mirena IUS are licensed as contraceptives, so barrier methods of contraception (e.g. condoms) should be used if using other treatments as an extra precaution.
All of the hormonal drugs carry side effects and are equally effective as treatments for endometriosis, so it’s often the side effects that will dictate the choice of drug.
Drugs used that mimic pregnancy:
- Combined oral contraceptive pill
- Progestagens
- Mirena IUS
Pregnancy is characterised by higher levels of progesterone, thus taking progestagens (the synthetic form of progesterone) mimics the state of pregnancy. During pregnancy, the endometrium is thin and also inactive.
Drugs that mimic menopause:
GnRH analogues are a form of the naturally occurring GnRH, which is produced in a part of the brain called the hypothalamus. GnRH analogues stop the production of the hormones FSH and LH. The ovaries switch off and temporarily stop producing eggs and the hormone oestrogen.
Male hormone drugs – testosterone derivatives:
Danazol and Gestrinone are derivatives of the male hormone, testosterone. They lower oestrogen levels which directly switches off the growth of the endometrium (lining of the womb).