Norethisterone — Contraception & Hormone Guide | KiwiMeds
✅ Reviewed by a Registered Pharmacist NZ | Last updated: May 2026 | This information is for educational purposes only and does not replace advice from your doctor or pharmacist.
What is norethisterone?
Norethisterone is a synthetic progestogen (progesterone-like hormone) used in contraception and to treat hormone-related conditions. In New Zealand, it is found in the mini-pill (progestogen-only pill), hormone replacement therapy, and is used to delay periods.
What is it used for? (NZ context)
Norethisterone is used as a contraceptive (progestogen-only pill), to treat endometriosis, to manage heavy or painful periods, and to delay periods for special occasions. In NZ the progestogen-only pill (mini-pill) containing norethisterone (brand: Noriday) is funded by Pharmac.
How does it work?
Norethisterone thickens cervical mucus (preventing sperm from reaching the egg) and may also suppress ovulation. In treating heavy periods, it stabilises the uterine lining, reducing bleeding.
How to take it
As a mini-pill, take at the same time every day (within a 3-hour window) — consistency is critical for contraceptive effectiveness. Unlike the combined pill, there is no pill-free week. For period delay, norethisterone 5mg is taken 3 times daily starting 3 days before the expected period.
Common side effects
- Irregular periods or spotting — very common with the mini-pill
- Nausea
- Breast tenderness
- Mood changes
- Acne
Serious side effects to watch for
Norethisterone is generally well tolerated. Rare serious risks include blood clots (lower risk than combined oestrogen-progestogen pills). Alert your doctor to any unexplained leg pain, chest pain, or shortness of breath.
Important drug interactions
Some epilepsy medicines (carbamazepine, phenytoin) and the antibiotic rifampicin reduce norethisterone effectiveness — additional contraception is needed. St John’s Wort also reduces effectiveness.
NZ-specific information
Pharmac funding: Norethisterone-containing mini-pill (Noriday) is funded by Pharmac for contraception. The 5mg tablets used for period delay and endometriosis require a prescription and may not be fully funded.
Frequently asked questions
How late can I take my mini-pill before it fails?
Norethisterone mini-pill has a strict 3-hour window — if taken more than 3 hours late, use additional contraception (condom) for 48 hours. This makes it less forgiving than the combined pill.
Will I still get periods on the mini-pill?
Periods often become irregular or stop altogether on the mini-pill. Spotting is common. This is normal and not harmful. If you have no period for a long time and are concerned, take a pregnancy test.
Can I use norethisterone to delay my period for a holiday?
Yes — norethisterone 5mg tablets are often prescribed for period delay. Take 3 times daily starting 3 days before the expected period. Periods usually return within 2–3 days of stopping. See your doctor or pharmacist for a prescription.
💬 Talk to your pharmacist or doctor for personalised advice about norethisterone.
Reviewed by a Registered Pharmacist NZ | BPharm, Pharmacy Council of New Zealand
References & Further Information
The following New Zealand and international resources were used to inform this page: