Norethisterone (Primolut N)

Norethisterone is a medicine that mimics progesterone to delay menstruation. While it’s most commonly used to postpone periods, it can sometimes be prescribed to treat endometriosis, or as part of hormone replacement therapy.

The branded version, Primolut N, comes in 5 mg tablets. When taken three times a day at regular intervals, Norethisterone can delay your period for up to 17 days, affording you control over your menstrual cycle.

Norethisterone tablets delay menstruation by mimicking a hormone called progesterone. This hormone plays a key role in controlling the menstrual cycle and preparing the womb lining for pregnancy.

Normally, a drop in progesterone signals the body to shed the womb lining, which causes a period. By keeping progesterone levels high, Norethisterone prevents the shedding of the womb lining and delays menstruation.

When taken as directed, Norethisterone is a highly effective option to delay a period. Provided you meet the prescribing guidelines, it can be just what you need for short-term period control.

As far as period timing after treatment is concerned, research shows that up to 87% of women have a withdrawal bleed within 2–3 days of stopping treatment.

To be prescribed Norethisterone, you must be a woman over the age of 18.

Do not take Norethisterone if you:

• are allergic to any ingredient found in this medicine
• are pregnant or think you might be
• are breastfeeding
• have ever had a problem with blood circulation
• have symptoms of a blood clot
• have a condition that puts you more at risk of developing a blood clot
• have ever experienced a migraine with visual disturbances
• are recovering from a liver disease
• have liver tumours
• have diabetes with damaged blood vessels
• have a type of cancer which may be worsened by exposure to female sex hormones (such as breast cancer)
• experience unexplained vaginal bleeding
• have untreated endometrial hyperplasia

For more information about the risks of taking Norethisterone, consult the patient information leaflet.

Norethisterone works straight away to boost progesterone levels, but you must start taking your tablets three days before your period is due for it to work.

If you start taking it too close to your period, you won’t give your body enough time to respond to the medicine, and menstruation may occur.

If you take Norethisterone tablets too close to your period (within 3 days of its scheduled start time), it will not work as intended.

Norethisterone cannot stop a period once your body has already started the process of menstruation.

As with all prescription treatments, Norethisterone can cause side effects.

The most common Norethisterone side effects include:

• vaginal bleeding (including spotting)
• shorter periods with reduced blood flow
• headache
• nausea (feeling sick)
• swelling

Norethisterone can also slightly increase the risk of a blood clot. This is because the active ingredient is partially converted into oestrogen. If you have been told you are more at risk of developing a blood clot, speak to your doctor before taking this medicine. They may prescribe alternative treatment.

For a full list of side effects, consult the patient information leaflet.

You can take Norethisterone tablets for a maximum of 20 days (including the three days prior to your planned period). This means you can delay your period for up to 17 days.

The longer you take Norethisterone tablets, the higher your risk of experiencing side effects. Your doctor may recommend a shorter course of treatment if they think you are more at risk.

After you take your last tablet, you should get your period within 2-3 days, although timings may differ.

If you do not get your period within this time or your bleeding is highly irregular, consult your doctor for advice.

Usually, your cycle will shift depending on when you stop taking Norethisterone. After the withdrawal bleed, your next period typically arrives around 28 days later.

With that being said, everybody is different, and you may find your cycle naturally settles back into its usual rhythm.

No, Norethisterone is not a contraceptive and will not prevent you from becoming pregnant. Do not use this medicine as a replacement for birth control.

Make sure to use a barrier contraceptive like condoms when having sex during treatment with Norethisterone.

Yes, Norethisterone is generally safe when taken as prescribed. It has been used for many years to manage period timing and certain menstrual conditions.

However, Norethisterone tablets aren’t safe for everyone. Make sure to follow your doctor’s advice, especially if you have a history of blood clots, liver problems, or other health conditions listed in the patient information leaflet.

Safety is our number one priority at 121doc. For this reason, our doctors will only prescribe treatment if you meet the criteria in your online consultation.

A prescription from a trusted healthcare provider like 121doc ensures:

• safety during treatment
• effective results
• monitoring of side effects