Norethisterone is a synthetic form of the naturally occurring hormone progesterone. It works by maintaining elevated levels of progesterone in the body, which prevents the uterine lining from shedding. This action temporarily delays the onset of menstruation. Norethisterone is available in 5mg tablet form and is a prescription-only medicine, meaning a clinical assessment is required before it can be supplied (NHS, How Can I Delay My Period?).

To delay your period, you should begin taking Norethisterone three days before your period is expected to start. The usual dose is one 5mg tablet taken three times daily (approximately every eight hours). Continue taking the tablets for each day you wish to delay your period, for a maximum of 17 days. Your period should begin approximately two to three days after you stop taking the tablets. It is important to follow the dosing instructions carefully and not to start the course late.

No. Norethisterone, when prescribed for period delay, does not act as a contraceptive and will not prevent pregnancy. If you require contraception during this time, you should use an alternative method such as condoms. It is important to be aware of this distinction, as the dose and regimen used for period delay are different from those used in some hormonal contraceptive preparations.

Norethisterone for period delay should not be used if you are currently taking a combined oral contraceptive pill. If you are on the combined pill and wish to skip a period, your doctor or pharmacist may advise you to take two packs back-to-back instead. Norethisterone is also not suitable for those taking the progesterone-only pill (mini-pill), such as Cerazette. Always discuss your current medication with your prescriber before starting Norethisterone.

Side effects from Norethisterone are uncommon but may include spotting or irregular bleeding, breast tenderness, stomach discomfort, headaches, and a reduced sex drive. The longer the period of delay, the more likely you are to experience side effects. In rare cases, Norethisterone may increase the risk of blood clots (venous thromboembolism). If you experience symptoms such as chest pain, sudden shortness of breath, or swelling in a leg, seek urgent medical attention.

You should start taking Norethisterone at least three days before your period is due. If you begin taking it after your period has already started, it will not be able to stop the bleeding. It is therefore important to plan and know when your next period is expected. If your cycle is irregular, speak to your prescriber for personalised advice on when to start the course.

Norethisterone for period delay is intended for occasional use only, for example, ahead of a holiday, sporting event, or special occasion. It should generally not be used more than once every three months (up to four times per year). If you find that you regularly need to delay or manage your periods, it may be more appropriate to discuss longer-term hormonal contraceptive options with your GP, as some can reduce or eliminate periods.

Yes. Your period should start within two to three days of stopping Norethisterone, and your subsequent menstrual cycles should continue as normal. In some cases, the first period after stopping the tablets may be heavier or longer than usual, but this typically settles by the following cycle. If your period does not return within seven days of stopping the tablets, you should take a pregnancy test and contact your GP.

NHS –Period: https://www.nhs.uk/conditions/periods/  
NICE – Heavy Menstrual Bleeding (NG88): https://www.nice.org.uk/guidance/ng88  
Medicines.org.uk – Norethisterone 5mg Tablets PIL: https://www.medicines.org.uk/emc/product/1494  
MHRA – Norethisterone Product Information: https://products.mhra.gov.uk/