Norethisterone (Oral) — NZ Medication Guide
📋 Reviewed by a Registered Pharmacist NZ — This information is for general educational purposes only and does not replace professional medical advice. Always consult your doctor or pharmacist before starting, stopping, or changing any medication.
What is Norethisterone (Oral)?
Norethisterone is a synthetic progestogen used for heavy menstrual bleeding, endometriosis, and postponement of menstruation. This medication is funded by Pharmac for menstrual disorders.
What is Norethisterone (Oral) Used For?
Norethisterone is used to treat heavy, painful, or irregular periods, endometriosis, premenstrual syndrome, postponement of menstruation (period delay), and as a component of combined hormonal contraceptives and HRT.
How Does Norethisterone (Oral) Work?
Norethisterone binds to progesterone receptors in the uterus, inducing endometrial decidualisation and atrophy — reducing endometrial proliferation and shedding. In high doses, it also suppresses LH/FSH and may inhibit ovulation. It also has weak oestrogenic and androgenic activity.
How to Take Norethisterone (Oral)
For period delay: 5 mg three times daily starting 3 days before expected period, continuing for up to 14 days. For heavy menstrual bleeding: 5 mg three times daily for 10–14 days. Period will occur 2–3 days after stopping. Not recommended as a reliable contraceptive at these doses.
Common Side Effects of Norethisterone (Oral)
- Breakthrough bleeding or spotting
- Nausea
- Headache
- Breast tenderness
- Mood changes
- Acne
- Weight changes
Serious Side Effects — Seek Medical Attention
Contact your doctor or call 111 immediately if you experience any of the following:
- VTE (small increased risk — particularly with prolonged high-dose use)
- Liver disorders (rare — particularly in predisposed patients)
- Depression
- Androgenic effects (acne, hirsutism) at higher doses
Drug Interactions
Norethisterone (Oral) may interact with other medicines. Always inform your doctor and pharmacist of all medications you are taking. Key interactions include:
- Enzyme inducers (carbamazepine, rifampicin — reduce norethisterone levels)
- Warfarin (variable effect)
New Zealand Prescribing Information
Norethisterone (5 mg tablets) is funded by Pharmac. It is widely used in NZ primary care for short-term management of heavy menstrual bleeding and period postponement (e.g., before travel or an event). Longer-term management of heavy bleeding should include investigation of the underlying cause (including endometrial assessment). The levonorgestrel IUD (Mirena®) is a more effective long-term treatment for heavy menstrual bleeding.
Frequently Asked Questions
Will norethisterone stop my period completely?
Norethisterone delays and suppresses menstruation while you are taking it. When you stop, a withdrawal bleed typically occurs within 2–3 days. It does not permanently stop periods.
Can I use norethisterone as a contraceptive?
Norethisterone at the standard period-delay and heavy menstrual bleeding doses (5 mg) is not a reliable contraceptive. Do not rely on it for contraception. If you require progestogen-only contraception, discuss appropriate options (mini-pill, implant, injection, hormonal IUD) with your doctor.
⚠️ Disclaimer: This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or a qualified health provider. In New Zealand, medication availability and funding may vary — check with Pharmac or your pharmacist for current information.
Reviewed by a Registered Pharmacist NZ
References & Further Information
The following New Zealand and international resources were used to inform this page: