As well as being used in a number of different forms of hormonal contraception, Norethisterone is a progestin that is also used for hormonal therapy in menopausal women and can be used to delay a period. It has also been used successfully to reduce pain in women with endometriosis. 

Norethisterone is a first-generation progestin with a long history of use. 

How does it work?

Norethisterone reduces pain in women with endometriosis by preventing ovulation, a process which can cause increased pain in women who have the condition1. Contraceptives containing Norethisterone work by thickening the cervical fluid which can prevent sperm from entering your uterus, and by thinning the lining of your uterus so that it is more difficult for a fertilised egg to implant. 

What is it used in? 

Combined Pill

Progestogen-only Pill

Is it androgenic?


What are the side effects? 

Norethisterone’s side effects vary depending on how it is taken. When it’s taken alongside other hormones, such as in a Combined Pill, it’s impossible to say which side effects are due to Norethisterone alone.

The following side effects have been recorded with oral use of Norethisterone3:

The following side effects have been recorded for Injections containing Norethisterone2:


  1. Kim JJ, Kurita T, Bulun SE. Progesterone action in endometrial cancer, endometriosis, uterine fibroids, and breast cancer. Endocrinology Review. 2013. 34(1):130-162. Available from: doi:10.1210/er.2012-1043
  2. Graham CA. The pill and women’s sexuality. BMJ. 2019. 364 Available from: doi: 
  3. Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press <> [13 August 2020]

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