Norethisterone
Is It Right for You?
A complete guide to Norethisterone — what it treats, how it works, dosages, side effects, and when a clinician may prescribe it following an online consultation.
What Is Norethisterone?
Norethisterone is a progestogen with several uses. It is used to delay periods, to treat heavy or painful periods and other menstrual problems, as a contraceptive, and as part of some HRT and endometriosis treatments.
It is taken as a tablet, with the dose and timing depending on the reason for use. It is available generically and is a long-established, versatile progestogen.
Norethisterone is a prescription-only medication in the UK. A licensed clinician can review why you need it and your medical history through a telehealth consultation and prescribe where appropriate.
What Conditions Is Norethisterone Used For?
Norethisterone is used for:
postponing a period for an event or holiday by taking tablets a few days beforehand.
helping to control heavy menstrual bleeding and related symptoms.
as a progestogen-only pill, or in combined preparations.
used within some menopause treatments and to manage endometriosis.
When used at higher doses to delay periods, norethisterone is not a reliable contraceptive. If you need contraception as well, use a separate method, and discuss this with your clinician.
How Does Norethisterone Work?
Norethisterone is a progestogen, a synthetic version of the natural hormone progesterone. It acts on the lining of the womb and on the hormonal signals that control the menstrual cycle.
To delay a period, it keeps the womb lining stable so it is not shed, postponing the bleed until the tablets are stopped. For heavy periods, it helps regulate and reduce the bleeding.
As a contraceptive, it thickens cervical mucus, thins the womb lining, and can affect ovulation, while in HRT it protects the womb lining from the effects of oestrogen.
Dosages & Administration
The correct dose depends on the type and severity of infection, age, weight, and kidney function. Always follow your clinician's instructions. The table below is for general reference only.
Administration Tips
For delaying periods, start the tablets a few days before your period is due and take them as directed; your period usually returns a few days after stopping.
For other uses, follow the exact schedule given, as the timing within your cycle matters for it to work properly.
Side Effects of Norethisterone
Side effects are usually mild. They can include hormonal effects and, rarely, effects on mood and circulation.
- Bloating or fluid retention
- Breast tenderness
- Nausea
- Headache
- Mood changes
- Spotting or changes in bleeding
- Reduced sex drive
- Signs of a blood clot - swollen, painful leg, chest pain, breathlessness
- Sudden severe headache or migraine with aura
- Yellowing of the skin or eyes
- Severe low mood or depression
- Severe allergic reaction
Progestogens like norethisterone carry a small risk of blood clots, which may be higher at the doses used to delay periods. Tell your clinician about any clotting risk factors, and seek urgent help for clot symptoms.
Drug Interactions
Always disclose all prescription drugs, over-the-counter medicines, vitamins, and supplements to your clinician or pharmacist before starting norethisterone.
Some epilepsy medicines, rifampicin, and St John's Wort can reduce effectiveness, particularly when used for contraception.
These can affect hormone levels; your clinician will advise on suitability and precautions.
Norethisterone can raise ciclosporin levels, which may need monitoring.
Tell your clinician about other hormones you take so treatment can be managed safely.
Important Warnings
The higher doses used to delay periods do not provide reliable contraception. Use a separate method if you need to avoid pregnancy.
Tell your clinician about smoking, migraine with aura, obesity, immobility, or a personal or family history of clots, which affect suitability, especially at higher doses.
Norethisterone may not be suitable with certain conditions, including some liver problems, a history of clots, or unexplained vaginal bleeding. Share your full history.
Do not take norethisterone if you might be pregnant unless specifically advised. Tell your clinician if there is any chance of pregnancy.
Speak to a Clinician About Treatment
Getting advice no longer means sitting in a waiting room. Through The GP Service, you can consult with a licensed clinician in minutes — from home, on your lunch break, or wherever works for you. If treatment is clinically appropriate, your clinician can issue a prescription during the consultation. A consultation does not guarantee a prescription.
The treatment you need, when you need it.
Norethisterone FAQs
Yes. A licensed clinician can review why you need it and your medical history through a telehealth consultation and prescribe norethisterone where appropriate, for example to delay a period.
It is usually started about three days before your period is due and taken three times a day. Your period normally returns a few days after you stop the tablets.
The higher doses used to delay periods are not reliable contraception. If you need contraception, use a separate method and ask your clinician for advice.
Occasional use to delay periods is common, but it is not intended for regular long-term use this way. Discuss ongoing needs with your clinician.
Some people get bloating, breast tenderness, nausea, headache, or mood changes. These are usually mild, but report anything severe or any clot symptoms.
It may be unsuitable if you have certain clotting, liver, or other conditions, or if you might be pregnant. A clinician will check your history before prescribing.