Period delay

Medical information

Written and reviewed by a team of doctors. Dr Fox is regulated by the CQC & GPhC.

Norethisterone 5mg - how it works

Norethisterone 5mg tablets can be taken three times daily to delay periods. Start tablets at least 3 days before the start of a period and continue for as long as needed. A period bleed will normally start 2 to 3 days, and possibly longer, after stopping norethisterone.

The balance of hormones changes during the menstrual cycle. During the time norethisterone tablets are being taken a period (shedding of the womb lining) will be delayed.

Women currently taking a contraceptive pill should not use norethisterone to delay their periods. Information about delaying periods whilst taking contraceptive pills or with Norethisterone can be found on the NHS page How can I delay my period?.

Norethisterone is NOT a contraceptive and will not prevent pregnancy.

Length of treatment

Dr Fox can supply sufficient norethisterone tablets to delay a period for up to 17 days, a maximum of 60 tablets. If period delay of less than 17 days is required, norethisterone is taken for fewer days and fewer tablets are required.

Norethisterone is routinely prescribed to delay periods, however it is only for occasional use and should not be requested more than once in 4 months. If more frequent treatment is required or period delay of more than 17 days is needed, a doctor should be consulted face-to-face.

Patients MUST read manufacturer's patient information leaflets supplied with tablets.

Other medications - interactions

If regular medication from the list below is being taken, patients should check with their doctors before taking norethisterone. The dose of regular medication may need to be adjusted.

• Medicines to treat epilepsy (e.g. phenytoin, carbamazepine)
• Antibiotic medicines to treat an infection (e.g. tetracyclines, rifampicin, co-trimoxazole)
• Antiviral medicines to treat HIV (e.g. ritonavir, nelfinavir)
• Anticancer medicines
• Herbal preparations containing St John's Wort (Hypericum perforatum)
• Aminoglutethimide, sometimes used in Cushing's syndrome
• Ciclosporin (for suppressing the immune system)
• Non-steroidal inflammatory drugs (NSAIDs) for treating pain and inflammation
• Medicines for high blood pressure

Cautions

Norethisterone side effects

As with all medications, norethisterone can cause side effects, although these are usually not troublesome. The most commonly reported side effects are bloating, breast tenderness, and loss of libido. Side effects are more likely if norethisterone is taken long term, rather than in a short course to delay periods.

Some women taking norethisterone experience fluid retention which can worsen pre-existing migraine, epilepsy, blood pressure and asthma.

Further information about side effects can be found in the manufacturer's patient information leaflet supplied with norethisterone tablets.

Sensitivity reactions to norethisterone

Very rarely, norethisterone may cause a severe allergic reaction which can in some cases be life-threatening. Sudden onset of some or all of the following require emergency treatment (very rare):

• wheezing
• difficulty breathing
• feeling faint
• swelling of the face or tongue
• swelling of the hands and feet
• intense itchy skin rash

Risk of Venous Thromboembolism (VTE)

All women have a small chance of having a blood clot in the veins of the legs or in the lungs or other parts of the body. The risk of a clot is very slightly increased if norethisterone is being taken. The risk of clots is also increased if the following apply:

• very overweight
• previous blood clot in the veins or lungs
• relatives have had blood clots
• immobility for long periods of time, for example after an operation or during a long haul flight
• after serious injury or have major surgery
• history of repeated miscarriage

Dr Fox supplies period delay tablets on prescription – you are required to answer a short medical questionnaire before your order can be completed.

Authored 17 November 2012 by Dr Tony Steele
Last updated 23 March 2021

Reviewed by Dr B. Babor, Dr Tony Steele
Last reviewed 05 September 2017

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