Primolut N tablets contain the active ingredient norethisterone, which is a synthetic version of the naturally-occurring female sex hormone, progesterone. It is used in a wide range of menstrual disorders. 

What is Primolut N used for?

  • Menstrual disorders such as painful periods (dysmenorrhoea), heavy menstrual bleeding (menorrhagia), irregular periods, continuous, heavy menstrual bleeding or premenstrual syndrome (PMS).
  • Endometriosis.
  • Delaying your menstrual period.

High doses of norethisterone can also be used to treat breast cancer, although the Primolut N brand of norethisterone is not licensed for this. 

How does Primolut N work?

  • Primolut N tablets contain norethisterone, which is a synthetic version of the naturally-occurring female sex hormone, progesterone.
  • In women, progesterone is responsible for the development of a healthy womb lining (endometrium) that is necessary for pregnancy. The body produces progesterone at certain times of the menstrual cycle, causing the womb lining to flourish. If a fertilised egg doesn't attach to the womb lining by the end of the monthly menstrual cycle, the levels of progesterone in the body decrease. This causes the body to shed the womb lining (a menstrual 'period'). If a fertilised egg successfully attaches to the womb lining by the end of the monthly cycle, progesterone levels in the body remain high. This helps maintain a healthy womb lining for the ongoing pregnancy.
  • Norethisterone mimics the effects of your natural progesterone and so can help regulate the healthy growth and normal shedding of the womb lining. It may be used in the treatment of menstrual disorders such as irregular or painful menstrual periods, PMS and endometriosis. It can also be used to postpone the start of your period for special circumstances, for example if you are travelling or taking part in a sporting event.

How do I take Primolut-N?

  • Norethisterone is usually taken on selected days during the menstrual cycle, depending upon the disorder that is being treated.
  • When in your cycle and how often to take this medicine depends on the reason that it has been prescribed. This will vary from person to person. It is important to follow the instructions given by your doctor. These should be printed on the dispensing label that your pharmacist has put on the packet of medicine. If you are unclear about anything you should ask your doctor or pharmacist for advice.
  • The tablets should be swallowed with a drink. They can be taken either with or without food.

Primolut N should be used with caution by

  • Women with decreased kidney or liver function.
  • Women with a history of blood clots in the blood vessels (thromboembolism).
  • Women with disorders that increase the risk of blood clots in the veins, eg antiphospholipid syndrome, antithrombin deficiency or factor V Leiden.
  • Women with a long-term condition called systemic lupus erythematosus (SLE).
  • Women who are obese.
  • Women who smoke.
  • Women with high blood pressure (hypertension).
  • Women with high cholesterol levels.
  • Women who suffer from asthma.
  • Women with heart failure.
  • Women with epilepsy.
  • Women with diabetes. This medicine may increase your blood sugar level. Women with diabetes may need to monitor their blood sugar more frequently during treatment with this medicine.
  • Women with a history of migraines.
  • Women with a history of depression.
  • Women with gallstones.
  • Women with a history of irregular brown patches appearing on the skin, usually of the face, during pregnancy or previous use of a contraceptive pill (chloasma). Women with a tendency to this condition should minimise their exposure to the sun or UV light while taking this medicine.
  • Primolut N should not be used by
  • Women who know or suspect they could be pregnant.
  • Women with abnormal vaginal bleeding, the cause of which has not yet been diagnosed.
  • Women with an active blood clot in a vein of the leg (deep vein thrombosis) or in the lungs (pulmonary embolism), or a history of these types of blood clot when the cause was not known.
  • Women with a history of angina, heart attack, stroke or mini-stroke (TIA).
  • Women with active liver disease or a history of severe liver disease if liver function has not returned to normal.
  • Women who have ever had a liver tumour.
  • Women with a history of jaundice, severe itching or a blistering skin rash called pemphigoid gestationis during pregnancy.
  • Women with a history of hormone-dependent breast cancer or genital cancer.
  • Women with rare inherited metabolic disorders called porphyrias.

Primolut N tablets contain lactose and are not suitable for people with rare hereditary disorders of galactose intolerance, Lapp lactase deficiency or glucose-galactose malabsorption.
This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.

If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

  • This medicine should not be used during pregnancy. If you think you could be pregnant you should stop taking this medicine and consult your doctor. Ask your doctor for further advice.
  • This medicine is not recommended for use by mothers who are breastfeeding. It may suppress the production of breast milk and alter the composition of the breast milk. Ask your doctor for further advice.

Possible side effects of Primolut N

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.

  • Changes in menstrual bleeding, eg irregular bleeding, spotting or sometimes stopping of bleeding.
  • Headache.
  • Migraine.
  • Nausea.
  • Abdominal pain.
  • Retention of fluid in the body tissues causing swelling (oedema).
  • Skin reactions such as rash and itching.
  • Dizziness.
  • Breast discomfort or tenderness.
  • Fatigue.
  • Difficulty sleeping (insomnia).
  • Depression.
  • Change in sex drive.
  • Weight gain.
  • Disturbance in liver function.
  • Jaundice.
  • Hair loss (alopecia).
  • Excessive hair growth (hirsutism).

Can I take norethisterone with other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to make sure that the combination is safe.

The following medicines may increase the breakdown of this medicine in the body, which could make it less effective:

  • aprepitant
  • barbiturates
  • bosentan
  • carbamazepine
  • cobicistat
  • crizotinib
  • dabrafenib
  • eslicarbazepine
  • efavirenz
  • fosaprepitant
  • fosphenytoin
  • griseofulvin
  • nevirapine
  • oxcarbazepine
  • perampanel
  • phenytoin
  • phenobarbital
  • primidone
  • topiramate
  • rifampicin
  • rifabutin
  • ritonavir
  • rufinamide
  • the herbal remedy St John's wort (Hypericum perforatum)
  • topiramate
  • vemurafenib.

This medicine may increase the blood levels of the following medicines and this could possibly increase the risk of their side effects:

  • ciclosporin
  • selegiline


Health Reference: Endometriosis