Levonorgestrel (Emergency Contraception) — 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 Levonorgestrel (Emergency Contraception)?
Levonorgestrel (Plan B / Postinor-1®) is a progestogen used as emergency contraception to prevent pregnancy after unprotected sex. This medication is available without prescription at NZ pharmacies (Postinor-1®); also available on prescription.
What is Levonorgestrel (Emergency Contraception) Used For?
Used as emergency contraception (the “morning-after pill”) to prevent pregnancy when taken within 72 hours (ideally within 24 hours) of unprotected sex or contraceptive failure. Most effective the sooner it is taken.
How Does Levonorgestrel (Emergency Contraception) Work?
Levonorgestrel works primarily by inhibiting or delaying ovulation, preventing sperm from fertilising an egg. It may also affect the cervical mucus and endometrium, though it does not interrupt an established pregnancy and is not an abortifacient.
How to Take Levonorgestrel (Emergency Contraception)
A single dose of 1.5 mg (one tablet) taken as soon as possible after unprotected sex. Most effective within 24 hours; still effective up to 72 hours (3 days). Take with food if nausea is a concern. A pregnancy test is recommended if your next period is late or different from usual.
Common Side Effects of Levonorgestrel (Emergency Contraception)
- Nausea (take with food to reduce)
- Headache
- Fatigue
- Dizziness
- Lower abdominal pain or cramping
- Breast tenderness
- Irregular bleeding or spotting after taking the pill
Serious Side Effects — Seek Medical Attention
Contact your doctor or call 111 immediately if you experience any of the following:
- Ectopic pregnancy (if pregnancy occurs despite treatment, there is an increased risk — seek urgent care if you have severe one-sided pelvic pain)
Drug Interactions
Levonorgestrel (Emergency Contraception) may interact with other medicines. Always inform your doctor and pharmacist of all medications you are taking. Key interactions include:
- Enzyme-inducing medicines (carbamazepine, phenytoin, rifampicin, St John’s Wort — reduce levonorgestrel efficacy; a double dose or copper IUD may be recommended)
New Zealand Prescribing Information
Postinor-1® (levonorgestrel 1.5 mg) is available without a prescription from all New Zealand pharmacies. It is not covered by Pharmac subsidy when purchased over-the-counter, but may be subsidised with a prescription. Women who are overweight (body weight >70 kg) may have reduced efficacy — a copper IUD inserted within 5 days is the most effective form of emergency contraception and is not affected by body weight.
Frequently Asked Questions
Is the morning-after pill the same as an abortion pill?
No — levonorgestrel prevents pregnancy before it is established; it does not terminate an existing pregnancy. If fertilisation and implantation have already occurred, it will not be effective.
How quickly should I take the morning-after pill?
The sooner you take it, the more effective it is. Within 24 hours: approximately 95% effective; 24–48 hours: approximately 85% effective; 48–72 hours: approximately 58% effective. After 72 hours, efficacy drops significantly.
⚠️ 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: