Norethisterone is a synthetic form of progesterone, a naturally occurring female sex hormone. It is referred to as a progestogen and is used to help to delay menstruation as it mimics the activity of progesterone.
Norethisterone can delay a period for up to 2 weeks for women who are not talking a birth control pill or are using the “mini pill”.
Norethisterone helps to maintain the integrity of the lining of the womb (uterus) and thus can be used to postpone the onset of menstruation for special circumstances, such as during holidays, taking part in sporting events or attending a festival.
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 does not attach to the womb lining by the end of the menstrual cycle, the levels of progesterone in the body decrease. This causes the body to shed the womb lining and results in a bleed, which is the familiar monthly menstruation period.
Taking norethisterone helps to prevent the breakdown of the lining of the uterus and thus bleeding does not occur until the drug is stopped.
Norethisterone is also used in the treatment of menstrual disorders such as irregular or painful menstrual periods, premenstrual syndrome and endometriosis.
To delay your period one norethisterone 5mg tablet should be taken three times a day commencing three days before a period is due to start.
It should be continued on a daily basis for up to a further two weeks but no longer than this. Taking the medication any longer may lead to heavier bleeding when the period starts.
The next period will usually begin within three days of stopping the norethisterone.
In order to delay a period for a week you will need only one pack (30 tablets) but for a delay of two weeks you should order the twin pack.
Along with their useful effects, some medicines can cause unwanted side-effects although not everyone experiences them. These usually improve as the body adjusts to the new medicine, but speak with a doctor or pharmacist if any of the following side-effects continue or become troublesome:
- Feeling sick,
- Breast tenderness,
- Changes in weight,
- Feeling tired or difficulty sleeping,
- Feeling depressed,
- Lack of interest in sex,
- Skin reactions
If any of the following uncommon but serious symptoms occur, stop taking norethisterone and contact a doctor for advice straightaway:
- Any feeling of pain and tightness in your chest,
- Any disturbances of your vision or hearing,
- Any unusually severe headaches,
- Jaundice (yellowing of your skin or the whites of your eyes).
Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken.
Norethisterone should be used with caution in:
- Decreased liver function.
- Decreased kidney function.
- Women with a history of depression.
- Heart failure.
- High blood pressure (hypertension).
- Women who suffer from migraines.
- Women with a history or risk of blood clots in the blood vessels (thromboembolism).
- Norethisterone should NOT be used in:
- Known or suspected pregnancy.
- Abnormal vaginal bleeding of unknown cause.
- Severe disease of the arteries, e.g. that has caused a stroke or heart attack.
- Women with a current blood clot in a vein of the leg (deep vein thrombosis) or in the lungs (pulmonary embolism).
- Disorders of bile excretion that cause jaundice (e.g. Dubin-Johnson or Rotor syndrome).
- Active liver disease.
- Previous history of or existing liver tumours.
- History of severe liver disease if liver function has not returned to normal.
- History of jaundice, severe itching, or rash called herpes gestationis during a previous pregnancy, or previous use of sex hormones.
- Rare hereditary blood disorders called porphyrias.
- Women who know they are going to have an operation in the next six weeks and women who are going to be immobile for a long time, e.g. following an accident.
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 norethisterone and inform your doctor or pharmacist immediately.
The patient information leaflet (PIL) is a leaflet containing specific information about medical conditions, doses and side effects. You can download a copy of the PIL here:
Patient Info Leaflet