Norethisterone

Norethisterone is a prescription-only tablet containing a synthetic form of the female hormone progesterone. Periods are triggered each month by a natural drop in your progesterone levels, which causes the lining of the womb to shed. Norethisterone works by keeping your progesterone levels artificially elevated, preventing this drop from occurring and therefore stopping the womb lining from shedding. This delays your period for as long as you continue taking the tablets. It is the only medicine licensed in the UK specifically for period delay and is a safe, reliable option for women who want to postpone their period for a holiday, special event, or other occasion. A short online consultation with one of our clinicians at Access Doctor is required before it can be prescribed.

Norethisterone can delay your period by up to 17 days when taken as directed. You start taking it 3 days before your period is due and can continue for up to 20 days in total. You can stop taking it earlier if you don't need to delay for the full duration — your period will arrive 2 to 3 days after you stop taking the tablets. It is recommended only for occasional use rather than regular or repeated use.

Start taking norethisterone 3 days before your period is expected to begin — this is important, as starting it any later may mean it doesn't have enough time to work and your period may still arrive. Take one 5mg tablet three times a day, spaced roughly 8 hours apart, and try to take each dose at the same time every day. Continue taking it for as long as you want to delay your period, up to a maximum of 20 days. Your period should arrive within 2 to 3 days of taking your last tablet. If your period doesn't arrive within 3 days of stopping, take a pregnancy test and speak to your GP.

No — this is one of the most important things to understand about norethisterone for period delay. Norethisterone at the dose used for period delay does not reliably prevent pregnancy. You can still ovulate and become pregnant while taking it. If you need contraception while using norethisterone, you must use a separate method of contraception — such as condoms, the pill, an implant, or a coil. Never rely on norethisterone alone to prevent pregnancy. If you think you may already be pregnant, do not take norethisterone and speak to your GP.

Most women tolerate norethisterone well, particularly when used for a short period. The most commonly reported side effects include breast tenderness, mild stomach discomfort, headaches, spotting or light bleeding between doses, low mood, reduced libido, fluid retention, and mild acne. These tend to be mild and usually resolve once you stop taking the tablets. The longer you take norethisterone, the more likely you are to experience some of these effects. Norethisterone also carries a slightly increased risk of blood clots — although the risk is low when used short-term, it is important to stay well hydrated and keep active while taking it. If you notice any signs of a blood clot — such as sudden pain, swelling or redness in your calf, chest pain, or shortness of breath — stop taking norethisterone immediately and call 999 or go to your nearest A&E.

Some women notice that their period is slightly heavier than usual after stopping norethisterone — this is because the womb lining has had longer than usual to build up. This is a normal and temporary effect and should settle by your next natural cycle. Most women find their periods return to their usual pattern within one to two months of completing a course of norethisterone. If you experience very heavy bleeding, bleeding that lasts significantly longer than usual, or you have any concerns after stopping, speak to your GP.

Norethisterone is not suitable for everyone. It should not be taken if you are pregnant, think you may be pregnant, or are breastfeeding. It is also not suitable for women with a history of blood clots, stroke, heart attack, breast or genital cancer, severe liver disease, or unexplained vaginal bleeding. Caution is advised for women with a high BMI (over 35), migraines, epilepsy, or significant cardiovascular risk factors. Always give your full medical history to your clinician at Access Doctor before starting norethisterone, so they can confirm it is safe for you.

No — norethisterone does not have any long-term effect on your fertility or future periods. Your menstrual cycle should return to its normal pattern within 2 to 3 months of stopping treatment. Research shows that normal ovarian activity typically resumes within 90 days for most women. If your periods do not return to normal within 3 months of stopping norethisterone, speak to your GP to rule out any other underlying cause.

Yes — this is actually a great idea and something that is often recommended. Because norethisterone can cause side effects such as spotting, breast tenderness, or mood changes in some women, trying it on a test run before your actual event means you will know in advance how your body responds to it. If it causes side effects that you find uncomfortable, speak with your GP or doctor for alternative options.