Part of 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. Taken three times daily starting at least 3 days before your expected period, it delays menstruation by maintaining elevated progesterone levels. Maximum 17 days delay. Not a contraceptive.
Norethisterone is the UK's only licensed prescription tablet for period delay. A synthetic progestogen, it works by maintaining elevated progesterone levels and preventing the uterine lining from shedding for as long as you take it. This guide is the complete clinical reference — dosing, safety, contraindications, drug interactions, and how to get a prescription online. For the step-by-step usage guide, see: How to take norethisterone. For side effects in depth, see: Norethisterone side effects.
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 expected period |
| Typical duration | 10-14 days |
| Maximum duration | Up to 20 days (providing up to 17 days of delay) |
| Period returns | Usually 2-3 days after stopping (occasionally up to a week) |
| Contraceptive? | NO — additional contraception required |
| Availability | Prescription only; online consultation available |
How Norethisterone Works
During the normal menstrual cycle, progesterone levels drop at the end of the luteal phase, signalling the uterine lining to shed. Norethisterone mimics progesterone, keeping levels artificially elevated and maintaining the lining — postponing menstruation for as long as you continue taking the tablets. Once stopped, progesterone falls and the period begins within 2-3 days.
Critical: Norethisterone cannot stop a period that has already started. You must begin at least 3 days before your expected start date — if your period begins before you start the tablets, they will not be effective.
How Effective Is It?
When taken correctly, norethisterone is highly effective at delaying menstruation. Around 1 in 10 women experience light spotting or breakthrough bleeding while taking it — this does not mean the medication has failed and is not a reason to stop. Heavy bleeding while taking norethisterone warrants contact with your prescriber.
Who Should Not Take Norethisterone
| Contraindication | Reason |
|---|---|
| Pregnancy | Not appropriate during pregnancy; speak to GP if pregnant |
| History of blood clots (DVT or PE) | Norethisterone may increase clotting risk in predisposed individuals |
| Severe liver disease | Norethisterone is metabolised by the liver; impaired function affects safety |
| Hormone-sensitive cancers | Including oestrogen- or progesterone-receptor-positive breast cancer |
| Unexplained vaginal bleeding | Cause should be investigated before any hormonal treatment |
| Breastfeeding | Passes into breast milk; speak to prescriber for alternatives |
| Severe arterial or cardiovascular disease | Requires careful clinical assessment before prescribing |
Side Effects
Norethisterone is generally well tolerated for short-term use. Common side effects include breast tenderness, bloating and fluid retention, nausea, headache, mood changes, spotting, and reduced libido. For a detailed breakdown of each side effect, frequency, and what to do, see: Norethisterone side effects: full guide.
Seek urgent medical attention if you experience sudden chest pain, breathlessness, severe leg pain or swelling, or sudden severe headache while taking norethisterone. These could indicate a blood clot. Call 999.
Drug Interactions
Tell your prescriber about all medications before starting. Norethisterone interacts with:
- Antiepileptics — phenytoin, carbamazepine, phenobarbital, primidone, topiramate, oxcarbazepine (reduce norethisterone effectiveness)
- Rifampicin and rifabutin (tuberculosis antibiotics — significantly reduce effectiveness)
- HIV antivirals — ritonavir, nelfinavir (reduce effectiveness)
- St John's Wort — herbal supplement; reduces effectiveness
- Warfarin — norethisterone may affect anticoagulant control; INR monitoring needed
- Ciclosporin — norethisterone may increase ciclosporin levels
Other Conditions Norethisterone Treats
At different doses, norethisterone is also used for:
- Heavy periods (menorrhagia) — higher dose from day 5 to day 26 of the cycle
- Endometriosis — daily norethisterone suppresses endometrial tissue growth
- Premenstrual syndrome (PMS) — taken during the luteal phase to stabilise hormone levels
- As a component of some combined oral contraceptive pills
These uses are at different doses and schedules from period delay. Period delay does not provide contraceptive cover.
How to Get Norethisterone Online
1
Complete a short online consultation
Answer questions about your health history, medications, and suitability. Takes 3-5 minutes. Reviewed by a GPhC-registered pharmacist independent prescriber.
2
Prescriber review
A prescriber reviews your answers, checks for contraindications, and issues a prescription if appropriate. Same working day if submitted 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?
Norethisterone works immediately once you start it, as long as you began at least 3 days before your expected period. It maintains elevated progesterone levels continuously, postponing menstruation for as long as you continue the course.
Can norethisterone stop a period once it has started?
No. It must be started at least 3 days before your expected period start date. Once bleeding has begun, norethisterone cannot stop it.
How many days can I delay my period?
Up to 17 days with norethisterone (taken for a maximum of 20 days continuously). For longer delays, the combined contraceptive pill running packs back-to-back may be a more suitable option.
Will my period be heavier after norethisterone?
It can be slightly heavier or longer, as the uterine lining has been maintained for longer than usual. This is expected and not a cause for concern. Your cycle should return to normal within 1-2 cycles.
Is norethisterone a contraceptive?
No. Norethisterone 5mg tablets for period delay do not prevent pregnancy. You must continue using your usual contraception throughout the course.
Does norethisterone affect fertility long-term?
No long-term effects on fertility have been established. Normal menstrual cycles return shortly after stopping.
Can I take norethisterone every month?
No. Norethisterone is for occasional use only. Regular monthly use increases side effect risk and is not recommended. Speak to a prescriber about longer-term cycle management if needed.
Can I get norethisterone online in the UK?
Yes. Norethisterone is prescription-only but available following an online consultation with GPhC-registered pharmacist independent prescribers. 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.