How is Norethisterone used in different ways?
In this article
What's the lowdown?
Norethisterone is a synthetic progesterone used in contraception and hormonal replacement therapy
You can also use norethisterone to delay periods
It can be found both in the combined contraceptive and the progesterone-only pill
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. You can read more about this in our guide to the best contraception for women with endometriosis.
How does it work?
The progestogen-only pill containing norethisterone works by thickening the cervical fluid which can prevent sperm from entering your uterus, and by thinning the lining of your uterus preventing a fertilised egg from implanting. When used alongside oestrogen in the combined pill, it also prevent ovulation.
Is it androgenic?
Yes.2 (Check out our ‘Androgens’ blog for more info on what this means).
Is norethisterone a contraceptive?
Yes, norethisterone is used in hormonal birth control pills like the ones below.
Combined Pill
Progestogen-only Pill
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 the 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:
- Menstrual cycle irregularities
- Mood changes
- Acne
- Breast tenderness
- Headaches
- Weight change
Can I get norethisterone over the counter?
With the new changes in law last year allowing pharmacists to prescribe and supply contraception, you can get norethisterone without needing a GP appointment. It is not quite over the counter but it reduces waiting times and barriers to contraception or period delay. You will still need to have a consultation of sorts with the pharmacist before they can give it to you.
Norethisterone and endometriosis
Norethisterone has been shown to be effective in treating the painful periods associated with endometriosis when taken 3 times a day for a 6 month period4. A study even showed that after 6 months of treatment, norethisterone successfully reduced the size of endometrial-related ovarian cysts called endometriomas5.
Norethisterone for menopause
Norethisterone is used alongside oestrogen to provide relief for menopausal symptoms in women. For women who still have a womb, they are unsuitable for progesterone only hormone replacement therapy so need to be in combination with oestrogen. Norethisterone is not suitable as a stand-alone prescription for hormone replacement therapy6.
Norethisterone for period delay
Norethisterone 5mg three times a day is licensed for use to delay periods. As it mimics high levels of progesterone in the body, it tricks the body into thinking it is not quite time for a period. It should be taken around 3 days before the start of your period and can be used for up to 4 weeks. We talk about the other ways to delay your period here!
Norethisterone for IVF
In IVF, norethisterone can be used to control the timing of your cycle ahead of egg collection. It is normally started around the mid-cycle six weeks before egg retrieval or transfer so your fertility specialist can better plan when to do each procedure.
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This article has been medically reviewed for factual and up to date information by a Lowdown doctor.
