Norethisterone

Norethisterone is a synthetic form of the female hormone progesterone. It has multiple medical uses, but is commonly taken to delay your period from starting.

About Norethisterone

• Norethisterone is a synthetic version of progesterone
• The most common reason for using norethisterone is to delay your period
• Norethisterone can delay a period for up to 17 days
• It can also be used to control or regulate the menstrual cycle, as well as treating endometriosis and premenstrual tension (PMT)
• You should use a non-hormonal form of contraception when taking norethisterone, such as condoms
• It is important to read the patient leaflet for a full list of side effects and cautions.

How Does Norethisterone Work?

The manmade progesterone in norethisterone works by mimicking the natural progesterone a woman makes during the menstrual cycle. When you take norethisterone, you keep the levels of progesterone in the body higher for longer than usual. 

High levels of progesterone make the body think that you have become pregnant. The body therefore maintains the thick uterine (womb) lining, and does not begin to shed it. This means that whilst taking norethisterone you are able to prevent a period from occurring.  

When you stop taking norethisterone, the levels of progesterone in the body fall. The body begins to shed the lining of the uterus and a period occurs.

Women may choose to take norethisterone to occasionally delay menstruation for a variety of reasons. These might include:

• Travel or holidays
• Sporting events
• Operations
• Religious events.

Norethisterone is not a contraceptive, and so you must use a non-hormonal form of contraception such as condoms if you are sexually active.

How is Norethisterone Taken?

To delay menstrual bleeding, one tablet of norethisterone is taken three times a day with water. You should start taking norethisterone three days before your period is due to start. 

Continue taking one tablet three times a day for no longer than 10 to 14 days. 

On stopping norethisterone, your period is likely to start within 2 to 3 days.

Dosage of Norethisterone

Each tablet contains 5 milligrams of norethisterone. One tablet should be taken three times a day for up to 14 days.

Are there any Side Effects?

Like all medications, norethisterone can have some side effects. The most common side effects include:

• Nausea (feeling sick)
• Tender breasts
• Tiredness
• Feeling bloated
• A reduced sex drive
• Headache.

Occasionally it can worsen some chronic conditions, including:

• Migraine
• High blood pressure
• Depression.

Your prescriber will discuss the risks with you as part of your Consultation.

More serious side effects include:

• Blood clots to the legs or lungs
• Yellowing of the skin or whites of the eyes due to liver problems
• Weakness on one side of the body.

If any of these occur, you should speak to a doctor immediately.

If you have a severe allergic reaction (anaphylaxis) including breathlessness, lip or tongue swelling, call 999 immediately.

Norethisterone Warnings

Norethisterone will not suit everyone. During the Consultation with UK Meds, you will be asked to complete a health questionnaire to check that norethisterone is suitable for you. Norethisterone may be unsuitable if you:

• Are breastfeeding
• Are pregnant, or could have become pregnant just before starting norethisterone
• Have unexplained or irregular vaginal bleeding
• Have a history of cervical or breast cancer (unless norethisterone is being used to treat breast cancer)
• Have ever had a blood clot to the legs or lungs
• Have recently had angina, a heart attack or stroke caused by a blood clot
• Have liver problems
• Have porphyria.

A prescriber from UK Meds will review your current medications, including any herbal remedies or supplements, to ensure that norethisterone will not interact with them. 

Once prescribed, you can order norethisterone online for home delivery.

More Information

• All about your menstrual cycle
• What is Norethisterone?