If you've got a holiday, wedding or another big event coming up, you may be wondering if there's a way to push your period if it's likely to disrupt your plans. Norethisterone is a licensed treatment that can delay your period back by several weeks when it's taken correctly, and it's the only progestogen licensed for this purpose in the UK.
This guide explains how norethisterone works, how and when to start taking it, what side effects to look out for, and who should speak to a doctor before using it.
How does norethisterone work?
Norethisterone is a progestogen, a synthetic version of the hormone progesterone that your body produces naturally.1 During a normal cycle, progesterone levels fall just before your period, which triggers the lining of your womb to shed. Norethisterone keeps your progesterone levels topped up, so the lining stays in place and your period is delayed until you stop taking it.
Clinical evidence supports this approach. In a randomised trial comparing norethisterone with the combined pill for delaying periods, women taking norethisterone were significantly less likely to experience breakthrough spotting, and the large majority said they'd choose the same method again.2 Unlike the combined pill, norethisterone doesn't contain oestrogen, which is why it's often the preferred option for people who can't take oestrogen-based contraception.
How to take norethisterone to delay your period
Norethisterone is licensed specifically for postponing menstruation, and the dosing is straightforward - one 5mg tablet, taken three times a day, starting three days before your period is due.1 Getting the timing right is key. If you start too close to when your period is due, the drop in progesterone may already be underway and the tablets won't be able to act against the decrease.
You keep taking norethisterone for as long as you want to delay your period, up to a maximum of 20 days which correlates to a 17 day delay. Once you stop, your period should start again within about two to three days.
Because the tablets need to be started three days ahead, the key to using norethisterone successfully is planning around your usual cycle length rather than waiting until symptoms of your period start. If your cycle is irregular and you're not confident when your period is due, it's worth speaking to a pharmacist or GP about the best time to start, as beginning too late is the most common reason norethisterone doesn't work as expected.
How long can norethisterone delay your period?
While NHS guidance states that norethisterone can be taken for up to three to four weeks if necessary, we prescribe up to a maximum of 20 days.3 It's meant for occasional, short-term use rather than as a regular way to manage your cycle. If you find you need to delay or control your periods often, you should consult your GP about longer-term options, such as a combined contraceptive pill taken back-to-back, since norethisterone on its own isn't designed for repeated frequent use.3
Also remember that norethisterone is not a contraceptive. If you're sexually active, you'll still need to use contraception, such as condoms, while taking it.3
Getting norethisterone in the UK
Norethisterone is a prescription-only medicine, so you'll need a consultation with a prescriber before you can take it, whether that's through your GP or an online pharmacy service. A short questionnaire covering your medical history, including any history of blood clots, migraines or liver problems, allows a pharmacist or clinician to check norethisterone is suitable and confirm the correct dose for your circumstances.
If you're planning a trip abroad, make sure to arrange your prescription with enough time to spare. You'll need to know roughly when your next period is due so you can start the tablets three days beforehand, and building in a few days' buffer gives you room if your dates shift.
What are the side effects of norethisterone?
Most people tolerate norethisterone well, and side effects are usually mild.4
- Bloating - common (affects up to 1 in 100 people), usually settles once you stop taking the tablets.
- Nausea - common, taking tablets with food can help.
- Headache - common, and usually mild.
- Breast tenderness or mood changes - less common, and typically temporary.
- Spotting or breakthrough bleeding - can happen, particularly if you start the tablets too late.
Blood clots are a rare but serious side effect of progestogens like norethisterone, which is why it isn't suitable for everyone. Side effects tend to be more noticeable the longer you take norethisterone for, so sticking to the shortest course that meets your needs is generally advised.4
Who shouldn't take norethisterone?
Norethisterone isn't suitable for everyone. You should avoid it, or discuss it carefully with a prescriber first, if any of the following apply:
- You have a history of blood clots (venous thromboembolism) or a strong family history of them
- You get migraines, as progestogen-only treatments like norethisterone are used with some caution in this group, though the evidence for this is limited3
- You have liver disease
- You have, or have had, breast cancer or another hormone-sensitive cancer1
- You're pregnant, think you might be pregnant, or are breastfeeding
If you're not sure whether norethisterone is right for you, a pharmacist consultation will cover your medical history before it's prescribed. This is also why you should be upfront about any conditions or medications during your consultation, even ones that feel unrelated to your period, since some interact with how norethisterone is broken down in the body.
When should you seek medical advice?
Speak to a doctor or pharmacist if:
- You develop sudden chest pain, breathlessness, or swelling and pain in one leg
- You get a sudden, severe headache or changes to your vision
- Your period doesn't start within a few days of stopping the tablets, in which case it's worth taking a pregnancy test and contacting your GP
- Side effects are severe or don't settle after a few days
Frequently Asked Questions
Does norethisterone delay your period?
Yes. Norethisterone is a licensed progestogen tablet that keeps your progesterone levels topped up, which stops the lining of your womb shedding and delays your period until you stop taking it.
What happens if you take norethisterone on the first day of your period?
Taking norethisterone once your period has already started won't stop it. The tablets need to be started three days before your period is due, giving your body time to hold off the drop in progesterone that triggers bleeding.
Can you buy norethisterone over the counter?
No. Norethisterone is a prescription-only medicine in the UK. You'll need a consultation with a GP or online pharmacy service before it can be prescribed.
How soon after stopping norethisterone will my period start?
Most people's periods start again within about two to three days of stopping the tablets. If your period hasn't returned within a week, it's worth taking a pregnancy test and contacting your GP.
How long can you take norethisterone for?
NHS guidance advises norethisterone can be taken for up to three to four weeks if needed. It's designed for short-term, occasional use rather than as a regular way to manage your cycle.
Is norethisterone safe to take?
For most people, norethisterone is safe when taken as directed and prescribed after a medical consultation. It isn't suitable for everyone though, including people with a history of blood clots, liver disease, or certain hormone-sensitive cancers, which is why a prescriber checks your medical history first.
Does norethisterone stop you getting pregnant?
No. Norethisterone is not a contraceptive, even though it's a hormone tablet. You'll still need to use contraception, such as condoms, if you're sexually active while taking it.
Can you take norethisterone if you're on the contraceptive pill?
Speak to your prescriber before combining norethisterone with other hormonal contraception. Delaying a period on a combined pill is often done differently, by running two packs back-to-back rather than adding norethisterone, so it's worth discussing which approach suits your situation.
References
- Wockhardt UK Ltd. Norethisterone 5mg Tablets. Summary of Product Characteristics (SmPC). Electronic Medicines Compendium; 2025. medicines.org.uk/emc
- Dean J, Kramer KJ, Akbary F, et al. Norethindrone is superior to combined oral contraceptive pills in short-term delay of menses and onset of breakthrough bleeding: a randomized trial. BMC Women's Health. 2019;19:70. doi:10.1186/s12905-019-0766-6
- Specialist Pharmacy Service. Choosing a medicine to delay periods. NHS SPS; 2025. sps.nhs.uk
- Pfizer Limited. Utovlan Tablets. Patient Information Leaflet (PIL). Electronic Medicines Compendium; 2025. medicines.org.uk/emc
This article is intended for informational purposes only and does not replace professional medical advice. Always read the patient information leaflet supplied with your medication and speak to a healthcare professional if you have specific concerns.