Is It Safe to Delay Your Period?

Whether delaying a period is healthy, who can and cannot take norethisterone, the blood clot risk, what happens to your cycle and fertility, how often you can do it, and common myths.

Part of the Period Delay Health Guide.

This clinically reviewed guide looks at the safety of delaying a period: whether it’s healthy, who can take norethisterone, the risks and the myths. For dosing and interactions, see how norethisterone works.

Is delaying your period healthy?

There is no medical need to have a monthly bleed. The bleed on hormonal contraception is a withdrawal bleed rather than a true period, and many people taking a combined pill run packs together to skip it, as directed for their brand. Delaying an occasional natural period with norethisterone works in a similar way: the womb lining is held in place for longer and then shed when you stop the tablets. For most people there is no lasting effect on health or on their cycle.

Who can and cannot take norethisterone

The Primolut N product information says it should be avoided while breastfeeding. Your prescriber will take extra care if you have a BMI over 30, smoke, are over 35, have migraines, epilepsy, asthma, or heart or kidney problems, or are planning a long-haul flight. Always give your full medical history during your consultation.

The blood clot risk

Part of each dose of norethisterone is converted in the body to ethinylestradiol, the oestrogen in the combined pill (about 4–6 micrograms for every 1mg, according to the Primolut N product information). That means the same blood clot warnings apply. The overall risk for a healthy person taking a short course is low, but it rises with a previous clot, a family history of clots, smoking, a higher BMI, being older, recent surgery or immobility, and long flights. If oestrogens are not suitable for you, NHS Specialist Pharmacy Service guidance lists medroxyprogesterone tablets (used off-label) as an alternative, although it isn’t suitable for people who have had a blood clot either — see period delay options compared.

Does it affect your cycle or fertility?

Norethisterone is used for short courses and is not known to cause long-term problems with fertility. Your period usually starts within 3 days of your last tablet, and the first bleed may be heavier or longer than usual. If your periods do not return to your usual pattern within a few months, speak to your GP.

How often can you do it?

Norethisterone is intended for occasional use, not every month. If you want to control your cycle regularly, talk to a prescriber about a longer-term option, such as a combined pill taken back to back or a hormonal coil, instead of repeating norethisterone courses. See our guide on delaying your period on the pill.

Myths and facts

• Myth: it’s harmful to delay your period. Fact: there is no medical need to bleed every month. The main risk of norethisterone is a small risk of blood clots, which your prescriber checks for.
• Myth: your period won’t come back. Fact: it usually starts within 3 days of your last tablet. If it doesn’t, take a pregnancy test and speak to your GP.
• Myth: it works as contraception. Fact: it doesn’t. Use condoms or another method while you take it.
• Myth: you can start it any time. Fact: you need to start at least 3 days before your period is due. It won’t reliably stop bleeding that has already started.
• Myth: natural methods work. Fact: there is no reliable evidence for lemon juice, apple cider vinegar or similar remedies. See how to delay your period naturally: what the evidence says.

When to seek medical advice

Call 999 for the warning signs in the box at the top of this page. Contact your prescriber if you notice heavy bleeding, low mood, or side effects that worry you. See our full side effects guide.

UK safety and prescribing information

• Legal status: norethisterone is a prescription-only medicine (POM). At Access Doctor it is prescribed only after an online consultation with a GPhC-registered pharmacist independent prescriber, who may decline and suggest an alternative or that you see your GP.
• Licence: it is the only progestogen licensed in the UK to delay periods (NHS Specialist Pharmacy Service). The dose is 5mg three times a day, starting 3 days before your period is due.
• Course length: take it for as long as your prescriber advises. The Primolut N licence describes courses of no longer than 10 to 14 days, and NHS Specialist Pharmacy Service guidance says it can be taken for up to 3 to 4 weeks if necessary.
• Not a contraceptive: use condoms or another method while you take it.
• Blood clots: part of each dose is converted in the body to ethinylestradiol, the oestrogen in the combined pill (about 4–6 micrograms for every 1mg, according to the Primolut N product information), so the same blood clot warnings apply. Your prescriber will check risk factors such as a previous clot, smoking, a BMI over 30, being over 35, recent surgery and long-haul travel.
• Pregnancy and breastfeeding: do not take it if you are or might be pregnant. The Primolut N product information says it should be avoided while breastfeeding, so ask your prescriber.
• Reporting side effects: you can report suspected side effects to the MHRA through the Yellow Card scheme website or the Yellow Card app.