Norethisterone Contraceptive Injection (Noristerat)
Effective short-term contraception for 8 weeks: Understand usage, benefits, side effects, and key precautions for Noristerat injection.
Norethisterone contraceptive injection, commonly known as Noristerat, is a progestogen-based method that provides effective contraception for approximately eight weeks after a single intramuscular dose. It is particularly suited for short-term use, such as bridging periods when switching contraceptives or awaiting vasectomy effectiveness.
About norethisterone contraceptive injection
| Type of medicine | Progestogen |
|---|---|
| Used for | Contraception |
| Also called | Norethindrone (in US); Noristerat® |
| Available as | Injection |
Norethisterone enantate, the active ingredient in Noristerat, is a synthetic progestogen mimicking the natural hormone progesterone produced by the ovaries. Administered as a depot injection, it offers a convenient, user-independent form of contraception ideal for short-term needs.
The primary mechanism involves
inhibition of ovulation
, preventing egg release from the ovaries. Additionally, it thickens cervical mucus to block sperm entry and thins the endometrial lining, reducing the likelihood of fertilized egg implantation.Noristerat is licensed for scenarios requiring high efficacy without daily compliance, such as post-vasectomy waiting periods or during rubella immunization when pregnancy must be avoided. When given correctly within the first five days of the menstrual cycle, it achieves a failure rate of about 1% per year.
Before having norethisterone contraceptive injection
Prior to administration, a thorough medical assessment is essential. Healthcare providers evaluate personal and family medical history, measure blood pressure, and perform targeted physical exams, including breast, abdominal, and pelvic checks if indicated. Pregnancy must be excluded before the first injection.
To make sure that it is safe for you to have the injection, tell your doctor if you:
- Have ever had an ectopic pregnancy or severe itching/yellowing of skin/eyes (jaundice) during pregnancy.
- Have a history of breast cancer or sex hormone-dependent cancers.
- Have experienced depression associated with hormonal contraceptives.
- Suffer from porphyria, a rare blood disorder.
- Have had an allergic reaction to any medicine.
- Are taking other medications, including over-the-counter, herbal remedies like St John’s wort, or treatments for epilepsy, fungal infections, or tuberculosis, as these can reduce efficacy.
Women with undiagnosed vaginal bleeding should not start until malignancy is ruled out. Those over 40 with prolonged amenorrhea require endometrial assessment. Regular monitoring is advised for liver conditions or pregnancy-prone diseases like cholestatic jaundice.
How norethisterone contraceptive injection is given
The injection is administered by a qualified healthcare professional, typically a doctor or nurse. Patients receive the manufacturer’s patient information leaflet (PIL) beforehand, detailing usage, side effects, and precautions.
- Timing: Ideally within the first 1-5 days of menstruation (day 1 being the first day of bleeding). Post-delivery/abortion, it can be given immediately if pregnancy is impossible.
- Dosage: 200 mg norethisterone enantate injected deeply into the gluteal muscle (buttock). It releases gradually into the bloodstream, providing protection for 8 weeks.
- Switching contraceptives: From combined oral contraceptives (COC), start immediately after the last active tablet. From progestogen-only methods, align with prior schedule and use barrier methods for 7 days if delayed.
No additional contraception is needed if timed correctly. Repeat injections are given every 8 weeks for ongoing use, though it’s primarily for short-term.
Getting the most from your treatment
To optimize benefits and manage expectations:
- Menstrual changes: Expect spotting, breakthrough bleeding, or irregular/heavy periods. Report persistent issues, as they may indicate infection or other causes. Amenorrhea before a repeat dose requires pregnancy exclusion.
- Duration: Strictly 8 weeks; inform your doctor of any delays in long-term plans.
- Weight management: Mild gain possible; maintain balanced diet and exercise.
- Breast self-exam: Check regularly for changes and report lumps.
- STI protection: Does not protect against HIV/AIDS or other infections; use condoms.
- Drug interactions: Inform providers of all medications. Efficacy reduced by enzyme inducers (e.g., epilepsy drugs, rifampicin).
Possible side-effects
Side effects vary; most are mild and transient. Menstrual disturbances are most common.
| Side Effect | Advice |
|---|---|
| Spotting | Speak with your doctor if concerned |
| Irregular periods | Let your doctor know |
| Headache | Ask pharmacist for painkiller |
| Nausea | Stick to simple meals; usually short-lived |
| Weight gain, skin reactions, dizziness | Speak with doctor if troublesome |
Less common: Mood changes, breast tenderness, acne. Seek immediate care for severe symptoms like jaundice, severe depression, or allergic reactions. Overdose is unlikely due to single-use presentation; treat symptomatically. Post-marketing data shows no combined hormonal contraceptive-like risks.
Frequently Asked Questions (FAQs)
Q: How long does Noristerat protection last?
A: Approximately 8 weeks from injection. Repeat doses must be timely to maintain efficacy.
Q: Does it stop periods?
A: Not always, but irregular bleeding, spotting, or amenorrhea is common. Consult if concerned.
Q: Can I use it long-term?
A: Licensed for short-term; prolonged use possible under monitoring, but not first-line.
Q: What if I’m switching from the pill?
A: Start immediately after last active COC tablet; use barriers for 7 days if later.
Q: Is it safe after childbirth?
A: Yes, if given soon post-delivery/abortion with no pregnancy risk.
Q: Does it protect against STIs?
A: No, use additional protection like condoms.
This guide synthesizes official data for informed decision-making. Always consult healthcare professionals for personalized advice.
References
- Norethisterone contraceptive injection – Patient.info — Patient.info. 2023-01-27. https://patient.info/medicine/norethisterone-contraceptive-injection-noristerat
- Noristerat 200mg, solution for intramuscular injection – (emc) — medicines.org.uk. Accessed 2026. https://www.medicines.org.uk/emc/product/1134/smpc
- Noristerat SmPC CCDS version 7 – NAFDAC Greenbook — NAFDAC. 2024-03-26. https://admin.greenbook.nafdac.gov.ng/uploadImage/smpc_files/2024/03/26/2024032600739cc4-5a71-523e-b1f4-66632ddfd6ad.pdf
- Progestin Contraceptive Injections – Merck Manuals — Merck Sharp & Dohme. Accessed 2026. https://www.merckmanuals.com/professional/gynecology-and-obstetrics/family-planning/progestin-contraceptive-injections
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