This guide sits inside our complete guide to periods in the UK.
Norethisterone for Period Delay: Dosing, Safety & How to Get It Online
The complete UK medication guide to norethisterone 5mg — how it works, when to start, contraindications, drug interactions, side effects, and how to get a prescription online via Access Doctor.
▶ What is norethisterone?
Norethisterone 5mg is a synthetic progestogen — and the only licensed prescription tablet for period delay in the UK. You take one tablet three times a day, starting at least 3 days before your period is due. It holds your progesterone levels up so the lining of your womb stays in place instead of shedding, which is what keeps your period at bay. Maximum delay: 17 days. And no — it is not a contraceptive.
Norethisterone is the only prescription tablet licensed in the UK for putting a period off. It is a synthetic progestogen: it keeps progesterone levels raised, and that stops the uterine lining from shedding for as long as you keep taking it. What follows is the full clinical picture — dosing, safety, who should avoid it, what it interacts with, and how to get a prescription online. If you would rather skip to the practical side, our step-by-step guide on how to take norethisterone covers the schedule, and norethisterone side effects covers what to expect.
Get Norethisterone Online
GPhC-registered pharmacist independent prescribers. Order before 3pm Monday-Friday for next-day delivery. GPhC pharmacy #9011198.
Order Norethisterone →Key Facts at a Glance
| Detail | Guidance |
|---|---|
| Standard dose | One 5mg tablet, three times daily |
| When to start | At least 3 days before your period is due |
| Typical duration | 10-14 days |
| Maximum duration | Up to 20 days (which gives up to 17 days of delay) |
| Period returns | Usually 2-3 days after stopping (occasionally up to a week) |
| Contraceptive? | NO — you still need additional contraception |
| Availability | Prescription only; online consultation available |
How Norethisterone Works
In a normal cycle, progesterone falls at the end of the luteal phase, and that drop is the signal for the uterine lining to shed. Norethisterone mimics progesterone, so levels stay artificially high and the lining stays put — your period is postponed for as long as you keep taking the tablets. Once you stop, progesterone drops and bleeding usually starts within 2-3 days.
Critical: norethisterone cannot stop a period that has already started. You need to begin at least 3 days before your expected start date. If your period arrives before you take the first tablet, the course will not work.
How Effective Is It?
Taken correctly, norethisterone is very good at holding a period off. Around 1 in 10 women notice light spotting or breakthrough bleeding while taking it — that does not mean the medication has failed, and it is not a reason to stop. Heavy bleeding while taking norethisterone is different: contact your prescriber if that happens.
Who Should Not Take Norethisterone
| Contraindication | Reason |
|---|---|
| Pregnancy | Not appropriate during pregnancy; speak to your GP if you are pregnant |
| History of blood clots (DVT or PE) | Norethisterone may increase clotting risk in people who are already predisposed |
| Severe liver disease | Norethisterone is metabolised by the liver, so impaired function affects safety |
| Hormone-sensitive cancers | Including oestrogen- or progesterone-receptor-positive breast cancer |
| Unexplained vaginal bleeding | The cause should be investigated before any hormonal treatment |
| Breastfeeding | It passes into breast milk; speak to your prescriber about alternatives |
| Severe arterial or cardiovascular disease | Needs careful clinical assessment before prescribing |
Side Effects
For short-term use, norethisterone is generally well tolerated. The common ones are breast tenderness, bloating and fluid retention, nausea, headache, mood changes, spotting, and a lower libido. For a detailed breakdown of each side effect, how often it occurs and what to do about it, see: Norethisterone side effects: full guide.
Seek urgent medical attention if you get sudden chest pain, breathlessness, severe leg pain or swelling, or a sudden severe headache while taking norethisterone. These could point to a blood clot. Call 999.
Drug Interactions
Tell your prescriber about everything you are taking before you start. Norethisterone interacts with:
- Antiepileptics — phenytoin, carbamazepine, phenobarbital, primidone, topiramate, oxcarbazepine (these reduce norethisterone's effectiveness)
- Rifampicin and rifabutin (tuberculosis antibiotics — they significantly reduce effectiveness)
- HIV antivirals — ritonavir, nelfinavir (reduce effectiveness)
- St John's Wort — a herbal supplement that reduces effectiveness
- Warfarin — norethisterone may affect anticoagulant control, so INR monitoring is needed
- Ciclosporin — norethisterone may push ciclosporin levels up
Other Conditions Norethisterone Treats
At different doses, norethisterone is also used for:
- Heavy periods (menorrhagia) — a higher dose taken from day 5 to day 26 of the cycle
- Endometriosis — daily norethisterone suppresses the growth of endometrial tissue
- Premenstrual syndrome (PMS) — taken during the luteal phase to steady hormone levels
- As a component of some combined oral contraceptive pills
These uses work to different doses and schedules than period delay. Period delay does not provide contraceptive cover.
How to Get Norethisterone Online
| Step | What happens |
|---|---|
| 1. Complete a short online consultation | You answer questions about your health history, your medications and whether the treatment suits you. It takes 3-5 minutes. A GPhC-registered pharmacist independent prescriber reviews it. |
| 2. Prescriber review | A prescriber reads your answers, checks for contraindications and issues a prescription if it is appropriate. Same working day if you submit before 3pm. |
| 3. Dispatched same day | Dispensed by our GPhC pharmacy and dispatched before 3pm Monday-Friday via Royal Mail Tracked 24. Plain, discreet packaging. |
Order Norethisterone Online
GPhC-registered pharmacy #9011198. Same-day prescription for consultations approved before 3pm Monday-Friday. Discreet next-day delivery.
Get Norethisterone →Frequently Asked Questions
How long does norethisterone take to work?
It starts working as soon as you begin taking it, provided you started at least 3 days before your period was due. It keeps progesterone levels steady, so your period is postponed for as long as you carry on with the course.
Can norethisterone stop a period once it has started?
No. It has to be started at least 3 days before your period is expected. Once bleeding has started, norethisterone will not stop it.
How many days can I delay my period?
Up to 17 days. That means a maximum of 20 days of continuous tablets. If you need a longer delay, taking combined contraceptive pill packs back-to-back may suit you better.
Will my period be heavier after norethisterone?
It can be a little heavier or longer than usual, because the lining of your womb has been kept in place for longer. That is expected and nothing to worry about. Your cycle usually settles within 1-2 cycles.
Is norethisterone a contraceptive?
No. Norethisterone 5mg for period delay does not prevent pregnancy, so keep using your usual contraception throughout.
Does norethisterone affect fertility long-term?
There is no evidence of long-term effects on fertility. Your normal cycle returns shortly after you stop.
Can I take norethisterone every month?
No — it is meant for occasional use. Using it every month raises the risk of side effects and is not recommended. If you need regular cycle control, talk to a prescriber about longer-term options.
Can I get norethisterone online in the UK?
Yes. It is prescription-only, but you can get it after an online consultation with a GPhC-registered pharmacist independent prescriber. Access Doctor (GPhC #9011198) offers same-day prescribing and next-day delivery.
References
- MHRA. SPC: Norethisterone 5mg tablets. 2024. medicines.org.uk/emc
- NICE. Heavy menstrual bleeding: assessment and management (NG88). Updated 2023. nice.org.uk
- NICE. Norethisterone: CKS prescribing information. 2024. cks.nice.org.uk
- NHS. Norethisterone. nhs.uk/medicines/norethisterone
- GPhC. Standards for registered pharmacies. pharmacyregulation.org
Medical disclaimer: This article is for informational purposes only. Norethisterone is a prescription-only medicine in the UK. A clinical consultation is required before it can be dispensed. In a medical emergency, call 999.