Got a holiday, wedding or another big event coming up? You might be wondering if there's a way to push your period back so it doesn't get in the way.
Norethisterone is a licensed treatment that can delay your period for up to 17 days when it's taken correctly. It's the only progestogen licensed for this in the UK.
This guide explains how norethisterone works, how and when to start taking it, which side effects to look out for, and who should speak to a doctor before using it.
Timing is everything. Norethisterone needs to be started three days before your period is due, not once it arrives.
How does norethisterone work?
Norethisterone is a progestogen, a man-made version of progesterone, a hormone your body makes naturally.1
During a normal cycle, your progesterone levels fall just before your period. That drop 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.
There's clinical evidence behind this approach. In a randomised trial comparing norethisterone with the combined pill for delaying periods, women on norethisterone were significantly less likely to have breakthrough spotting. Most said they'd choose the same method again.2
Unlike the combined pill, norethisterone doesn't contain oestrogen. That's why it's often the preferred option if you can't take oestrogen-based contraception.
How to take norethisterone to delay your period
Norethisterone is licensed specifically for delaying periods, and the dosing is straightforward. You take one 5mg tablet three times a day, starting three days before your period is due.1
Set three reminders a day, spaced roughly evenly, so it's easier not to miss a dose.
Getting the timing right is key. Start too close to your period, and the drop in progesterone may already be underway, so the tablets won't be able to stop it.
You keep taking norethisterone for as long as you want to delay your period, up to a maximum of 20 days. That gives you a delay of up to 17 days. Once you stop, your period should start within about two to three days.
Because you need to start three days ahead, plan around your usual cycle length rather than waiting for period symptoms. Cycle irregular, and not sure when your period is due? Speak to a pharmacist or GP about the best time to start, as starting too late is the most common reason norethisterone doesn't work as expected.
How long can norethisterone delay your period?
NHS guidance says norethisterone can be taken for up to three to four weeks if needed, but we prescribe it for up to a maximum of 20 days.3 It's meant for occasional, short-term use, not as a regular way to manage your cycle.
Find you need to delay or control your periods often? Speak to your GP about longer-term options, such as taking a combined contraceptive pill back-to-back. Norethisterone on its own isn't designed for frequent, repeated use.3
Remember, norethisterone isn't a contraceptive. If you're sexually active, you'll still need to use contraception, such as condoms, while you're taking it.3
Getting norethisterone in the UK
Norethisterone is a prescription-only medicine. That means you'll need a consultation with a prescriber first, either through your GP or an online pharmacy service.
A short questionnaire covers your medical history, including any history of blood clots, migraines or liver problems. That lets a pharmacist or clinician check norethisterone is suitable for you and confirm the right dose.
Planning a trip abroad? Sort your prescription out with plenty of time to spare. You'll need to know roughly when your next period is due so you can start three days beforehand, and a few days' buffer gives you room if your dates shift.
Ordering online? Allow time for delivery on top of the three days before your period is due.
What are the side effects of norethisterone?
Most people tolerate norethisterone well, and side effects are usually mild.4
- Bloating - this usually settles once you stop taking the tablets.
- Nausea - taking your tablets with food can help.
- Headache - usually mild.
- Breast tenderness or mood changes - typically temporary.
- Spotting or breakthrough bleeding - this 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 also tend to be more noticeable the longer you take it, so the shortest course that meets your needs is generally best.4
Chest pain, sudden breathlessness, or pain and swelling in one leg? Stop taking norethisterone and get urgent medical help.
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 these 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 limited^3^
- You have liver disease
- You have, or have had, breast cancer or another hormone-sensitive cancer^1^
- You're pregnant, think you might be pregnant, or are breastfeeding
Not sure whether norethisterone is right for you? A pharmacist consultation will go through your medical history before it's prescribed.
That's also why it's important to be upfront about any conditions or medicines during your consultation, even ones that seem unrelated to your period. Some can affect how your body breaks down norethisterone.
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.