Norethisterone
Norethisterone is a synthetic progestin (a man-made form of the female hormone progesterone) that works by stopping the lining of the uterus from growing and by causing the uterus to produce certain hormones. Norethisterone is used for Endometriosis and Abnormal uterine bleeding and secondary amenorrhea.
Also called: Utovlan (United Kingdom)
Pronunciation: nor-ETH-ih-ster-ohn.
- Generic name
- norethisterone
- Brand names
- Aygestin, Norlutate, Primolut N, Utovlan, Noriday
- Drug class
- Progestin
- Form
- Tablet
- Route
- Oral tablet
- Legal status
- Prescription-only medicine
Availability and supply rules vary by country
Trade names by country: United Kingdom · Australia · India · Nepal · New Zealand
Australia: Primolut N, Noriday 28 Day · Full directory
What norethisterone is and how it works
Norethisterone is a synthetic progestin (a man-made form of the female hormone progesterone) that works by stopping the lining of the uterus from growing and by causing the uterus to produce certain hormones. (1) (2) (3)
Approved uses include treatment of endometriosis, secondary amenorrhea (missed periods) in women who are not pregnant or menopausal, and abnormal uterine bleeding due to hormonal imbalance. The exact licensed uses and brand names depend on the country. This monograph does not cover the lower-dose norethisterone products used for contraception.
Mechanism of action: how norethisterone works
Norethindrone acetate is a synthetic oral progestin. It works by inhibiting the growth of an estrogen-primed endometrium, producing secretory transformation, and altering gonadotropin and other hormonal feedback. (2)
What is Norethisterone used for?
Endometriosis
Norethisterone may be used to treat endometriosis. The US label describes an initial dose of 5 mg, increased by 2.5 mg every two weeks up to 15 mg daily, held for six to nine months. The Australian product information lists endometriosis as an approved indication. A clinician must select the dose and schedule based on the exact product. (1) (2) (3)
Abnormal uterine bleeding and secondary amenorrhea
It is used to treat abnormal uterine bleeding due to hormonal imbalance (when no structural cause such as fibroids or cancer is found) and to bring on a normal menstrual cycle in certain women who have stopped menstruating and are not pregnant. The US label gives a range of 2.5 to 10 mg daily for 5 to 10 days. (1) (2)
Other country-specific uses
The Australian product information also lists premenstrual syndrome, delay of menstrual period, and as an adjunct to estrogen hormone replacement therapy. These uses may not be approved in every country; check the local product label. (3)
Before taking norethisterone
Do not take / not appropriate for
- Do not take norethisterone if you know or suspect you are pregnant, or as a pregnancy test. (all products) (2)
- Do not take norethisterone if you have undiagnosed vaginal bleeding. (all products) (2)
- Do not take norethisterone if you have or have had breast cancer, active or recent arterial thromboembolic disease (such as stroke or heart attack), active blood clots in the legs or lungs, significant liver disease, or a known hypersensitivity to the drug. (all products) (1) (2)
Tell your clinician about
- Any previous heart attack, stroke, mini-stroke, chest pain, or coronary artery disease.
- A history of blood clots, thrombophilia, or any condition that makes blood clot more easily.
- Breast cancer, any unexplained vaginal bleeding, liver problems, or yellowing of the skin or eyes.
- Migraine headaches, seizures, depression, high blood pressure, high cholesterol, diabetes, lupus, or heart or kidney disease.
- Smoking or tobacco use.
- Pregnancy, plans for pregnancy, or breastfeeding. Norethisterone is contraindicated during pregnancy. Detectable amounts of progestins have been found in breast milk.
- All prescription and non-prescription medicines, vitamins, supplements, and herbal products you are taking, especially St. John's wort.
Norethisterone dosage and how to take it
- Take norethisterone tablets by mouth exactly as directed by your prescriber. The dose, schedule, and duration depend on the condition being treated.
- Do not take more or less of it, or take it more often, than prescribed.
- Continue to take the tablets even if you feel well. Do not stop taking norethisterone without talking to your doctor first.
- For endometriosis, the US label describes a starting dose of 5 mg daily for two weeks, with increases of 2.5 mg per day every two weeks until 15 mg per day is reached; treatment may be held at this level for six to nine months.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3)
Missed dose
Take the missed dose as soon as you remember. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not double the dose to make up for a missed one.
Overdose
If the patient has collapsed, had a seizure, has trouble breathing, or cannot be awakened, immediately call emergency services. For other suspected overdose situations, contact a poison control helpline or poison information service. (1)
Norethisterone side effects
Side effects can vary. Many are mild and reversible. Some rare effects are serious and require prompt medical attention.
Irregular vaginal bleeding or spotting
What to notice: Bleeding or spotting at unexpected times, or a change in the usual menstrual flow.
What to do: Tell your doctor, especially if the bleeding is heavy or persistent. (1)
Breast changes, nausea, and bloating
What to notice: Enlarged or tender breasts, nausea, vomiting, or bloating.
What to do: Discuss with your doctor if these symptoms are severe or do not go away. (1)
Mood, sleep, and skin changes
What to notice: Acne, brown patches on the face, hair loss, facial hair growth, weight changes, difficulty sleeping, or mood swings.
What to do: Report any concerning or persistent changes to the prescribing clinician. (1)
Symptoms of a blood clot
What to notice: Pain, warmth, or heaviness in the back of the lower leg; shortness of breath; coughing up blood; sudden sharp or crushing chest pain; heaviness in the chest; slow or difficult speech; dizziness or faintness; weakness or numbness of an arm or leg; or swelling of the arms, hands, feet, ankles, or lower legs.
What to do: Seek immediate medical attention. (1)
Visual abnormalities
What to notice: Sudden partial or complete loss of vision, blurred vision, double vision, bulging eyes, or a new type of migraine headache.
What to do: Get medical attention immediately; a clinician will decide whether norethisterone needs to be stopped pending an eye and neurological examination. (1) (2)
Severe allergic reaction or serious systemic symptoms
What to notice: Hives, rash, itching, difficulty breathing or swallowing, yellowing of the skin or eyes, depression, sudden severe pain in the abdomen, or missed periods.
What to do: Contact your doctor immediately. (1)
Serious warnings
Cardiovascular events (blood clots, stroke, heart attack) — emergency
Symptoms: Sudden shortness of breath, chest pain, severe headache, trouble speaking, weakness or numbness on one side of the body, or severe leg pain with swelling.
Visual disturbance — emergency
Symptoms: Sudden loss of vision, double vision, or bulging eyes.
Action: Get medical attention immediately; a clinician will decide whether norethisterone needs to be stopped and will arrange appropriate examination. (1) (2)
Suspected pregnancy — action_required
Symptoms: A missed period or a positive pregnancy test while taking norethisterone.
Action: Contact the prescribing clinician immediately for advice. (1) (2)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| St. John's wort | This herbal product may reduce the effectiveness of norethisterone or increase the risk of side effects. | Do not start taking St. John's wort while on norethisterone without discussing it with your healthcare provider. (1) |
| Laboratory tests | Norethisterone can affect the results of certain blood and hormone tests. | Before having any laboratory test, tell your doctor and the laboratory personnel that you are taking norethisterone. (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy and breastfeeding
Norethisterone is contraindicated during pregnancy because it may cause fetal harm when given to pregnant women. If pregnancy is suspected while taking the medicine, contact the prescriber right away. Detectable amounts of progestins have been found in breast milk; discuss the risks and benefits with your doctor if you are breastfeeding. (1) (2)
People with cardiovascular risk factors
Patients with risk factors for arterial vascular disease (such as hypertension, diabetes, tobacco use, high cholesterol, obesity) or venous thromboembolism (such as a personal or family history of blood clots, obesity, systemic lupus erythematosus) should be managed appropriately by their prescriber, according to the US label. Tell your prescriber about all risk factors. (2)
Monitoring
Before starting
- Confirm that the patient is not pregnant and does not have contraindications such as undiagnosed vaginal bleeding, breast cancer, or recent cardiovascular events.
- Assess the specific diagnosis and intended treatment goal (endometriosis, secondary amenorrhea, or abnormal uterine bleeding) against the local product label.
- Review the patient's full medical history, including cardiovascular risk factors, migraine, depression, and liver function.
- Select the dose and schedule based on the exact indication and product information.
During treatment
- Monitor for breakthrough bleeding, menstrual response, and symptoms of the underlying condition.
- Be vigilant for signs of thromboembolic or visual complications, especially in patients with risk factors.
- Keep all follow-up appointments and laboratory tests as directed by your doctor.
Storage
Keep the medication in its original container, tightly closed, and out of reach of children. Store at room temperature away from excess heat and moisture (do not store in the bathroom). The Australian label for Primolut N specifies storage below 30 degrees Celsius. Dispose of unneeded medication through a medicine take-back program; do not flush it down the toilet.
Professional information
Clinician-facing context only. Use the current local product labelling and indication-specific guidelines. The contraceptive use of norethisterone is a separate product category not covered here.
United States (US FDA label)
Indication: Endometriosis
Dose summary: Initial daily dosage of 5 mg norethindrone acetate for two weeks. Dosage should be increased by 2.5 mg per day every two weeks until 15 mg per day of norethindrone acetate is reached. Therapy may be held at this level for six to nine months or until annoying breakthrough bleeding demands temporary termination.
Renal context: Renal impairment dosing is not specifically addressed in the available research notes; decisions require individual specialist assessment. (2)
United States (US FDA label)
Indication: Secondary amenorrhea, abnormal uterine bleeding due to hormonal imbalance
Dose summary: 2.5 to 10 mg norethindrone acetate may be given daily for 5 to 10 days. Progestin withdrawal bleeding usually occurs within three to seven days after discontinuing therapy.
Renal context: Renal impairment dosing is not specifically addressed; requires individual assessment. (2)
Australia (AU TGA/ARTG)
Indication: All listed indications (including dysfunctional bleeding, amenorrhoea, premenstrual syndrome, delay of menstrual period, endometriosis)
Dose summary: No specific dosing schedule is detailed in the available research notes; refer to the full Australian product information for Primolut N.
Renal context: No specific renal adjustment is provided in the available notes. (3)
Hepatic guidance
Norethisterone is contraindicated in patients with significantly impaired liver function or liver disease. Use local product information and specialist judgement; no impairment-specific dose adjustment is provided in these notes.
Overdose note
Product identification, dose reconstruction, and supportive monitoring are required. (2)
Frequently asked questions
Can norethisterone be used as a contraceptive?
Lower-dose norethisterone products (often called the 'mini-pill' or progestin-only pill) are used for contraception, but this monograph does not cover those products. The doses and brands discussed here are for managing gynecological conditions and are not approved for contraceptive use. (1)
What should I do if I miss a period while taking norethisterone?
A missed period could be caused by the medicine, but it could also indicate pregnancy. Norethisterone must not be taken during pregnancy. Contact your prescriber right away if you miss a period or suspect you might be pregnant, so they can assess your situation and advise you appropriately. (1) (2)
Can I stop taking norethisterone as soon as I feel better?
No. Norethisterone helps control your condition but it does not cure it. You should not stop taking it without talking to your doctor, even if you feel well. Stopping treatment early can cause your symptoms to return. (1)
What is the mechanism of action of norethisterone?
Norethindrone acetate is a synthetic oral progestin. It works by inhibiting the growth of an estrogen-primed endometrium, producing secretory transformation, and altering gonadotropin and other hormonal feedback. (2)
References
- Norethindrone: MedlinePlus Drug InformationMedlinePlus, U.S. National Library of Medicine · United States · accessed 2026-10-13 · source 1
- NORETHINDRONE ACETATE tablet, prescribing informationU.S. National Library of Medicine (DailyMed) / FDA · United States · accessed 2026-10-13 · source 2
- PRIMOLUT N norethisterone 5 mg tablet – Consumer Medicine Information summaryhealthdirect Australia · Australia · accessed 2026-10-13 · source 3
- Norethisterone Country‑Brand Verification (harvested September 2026)Various national prescribing/dispensing registers (NHSBSA, PBS, Pharmac, 1mg) · Multiple (UK, Australia, New Zealand, India) · accessed 2026-09-25 · source 4
Brand names by country
Single-ingredient norethisterone names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United Kingdom
- Primolut Nreference source
- Utovlanreference source
- Noridayreference source
Australia
- Primolut Nreference source
- Noriday 28 Dayreference source
India
Source-listed products; local stock and regulatory approval have not been confirmed. Check the exact ingredient, strength, and formulation with a pharmacist.
- Norlut-N TabletTablet · 5mg · Cipla Ltdpharmacy source recorded · checked 2026-09-24
- Rethrowel 5mg TabletTablet · 5mg · Leeford Healthcare Ltdpharmacy source recorded · checked 2026-09-24
- Prevent N 5mg TabletTablet · 5mg · Intas Pharmaceuticals Ltdpharmacy source recorded · checked 2026-09-24
- Primolut-N TabletTablet · 5mg · Zydus Healthcare Limitedpharmacy source recorded · checked 2026-09-24
- Regestrone 5mg TabletTablet · 5mg · Torrent Pharmaceuticals Ltdpharmacy source recorded · checked 2026-09-24
- Crina-NCR 10mg TabletTablet CR · 10mg · Alembic Pharmaceuticals Ltdpharmacy source recorded · checked 2026-09-24
- Sysron-NCR TabletTablet CR · 10mg · Systopic Laboratories Pvt Ltdpharmacy source recorded · checked 2026-09-24
- Gynaset 10mg Tablet CRTablet CR · 10mg · Mankind Pharma Ltdpharmacy source recorded · checked 2026-09-24
- Sysron Ntablet · 5 mg · Systopic Laboratoriespharmacy source recorded
- Nostra CRcontrolled-release tablet · 10 mg, 15 mg · Corona Remedies Pvt Ltdpharmacy source recorded
- Nortas CRcontrolled-release tablet · 10 mg · Intas Pharmaceuticals Ltdpharmacy source recorded
Nepal
Source-listed products; local stock and regulatory approval have not been confirmed. Check the exact ingredient, strength, and formulation with a pharmacist.
- DubogenTablet · 5mg · Unichem Laboratories Ltd.reference source · checked 2026-09-24
- FemitroneTablet · 5mg · Lomus Pharmaceutical Pvt. Ltd.reference source · checked 2026-09-24
- MartinorTablet · 5mg · Walter Bushnellreference source · checked 2026-09-24
- Noreta HrtTablet · 5mg · Zydus Pharmaceuticalsreference source · checked 2026-09-24
- NorgestTablet · 5mg · Micro Labs Ltd.reference source · checked 2026-09-24
- RegestroneTablet · 5mg · Novartis India Ltd.reference source · checked 2026-09-24
New Zealand
- Noridayreference source
- Primolut Nreference source