Period delay — how it works
Reviewed by the My London Pharmacy clinical team, Yvonne Lim, Pharmacist Independent Prescriber
·29 July 2026
·6 min read
Quick answer
Period delay uses a short course of the hormone progestogen to postpone a period, usually for a holiday, event or competition. In the UK this is commonly done with norethisterone tablets, started a few days before your period is due and stopped when you want your period to return, typically within a few days.
What period delay is
Period delay is a short, planned way to push back a period you would rather not have at a particular time, such as during a holiday, a wedding, a religious occasion, exams or a sporting event. It is not contraception and it is not a long-term treatment; it is a temporary measure used for a specific occasion. Once you stop the tablets, your natural cycle returns and periods continue as before.
The most commonly used option in the UK is a progestogen tablet. Progestogen is a hormone your body already produces, and it plays a key role in maintaining the womb lining during the second half of your cycle. By keeping progestogen levels up with a tablet, you can hold off the natural drop in hormones that normally triggers a period, delaying the bleed until you decide to stop. It is a well-established approach that many people use occasionally, and it does not affect your long-term fertility.
How period delay tablets work
A period starts when levels of the hormone progesterone fall towards the end of your cycle, prompting the womb to shed its lining. Norethisterone is a progestogen that keeps these levels artificially high, which signals the womb to maintain its lining rather than shed it. As long as you keep taking the tablets, the period is held back. When the tablets stop, hormone levels fall and the period is allowed to begin.
The course is usually started around three days before your period is expected. It is then taken regularly, typically three times a day, for as long as you want to delay the bleed, up to a maximum length recommended by the prescriber. Because the effect depends on keeping hormone levels steady, consistency matters: taking the tablets at evenly spaced times and not missing doses gives the most reliable result. When you stop, the hormone level falls and your period usually arrives within two to three days.
Who period delay suits, and who should be cautious
Period delay suits many people who have an occasional, planned reason to postpone a period and do not need ongoing contraception. It can be a practical, discreet option for a one-off event. Because it involves a hormone, a clinician will check your medical history first to make sure it is appropriate for you, rather than it being something to start without advice.
It is not suitable for everyone. People with a history of blood clots (deep vein thrombosis or pulmonary embolism), certain heart or liver conditions, some hormone-sensitive cancers, or unexplained vaginal bleeding may be advised against it or need an alternative. Pregnancy should be excluded first, and any interactions with other medicines considered, as some medications can affect how it works. Age, weight, smoking status and blood pressure may also be relevant. This is why period delay is a prescription treatment that follows a short assessment rather than something to start unsupervised.
How to take it and when to stop
Timing matters. You usually begin the tablets a few days before your period is due, keep taking them across the days you want to stay period-free, and then stop on the day you are happy for your period to return. Missing doses or starting too late can allow bleeding or spotting to break through, so it helps to plan carefully around the exact dates of your event and set reminders for each dose.
- Start around three days before your period is expected.
- Take each dose regularly and at evenly spaced times, as directed by the prescriber.
- Do not exceed the maximum length of the course advised for you.
- Stop when you want your period to return; it usually comes within a few days.
If you also want ongoing cycle control rather than a one-off delay, some people use certain hormonal contraceptives to manage the timing of periods instead, for example by running packs together under guidance. A clinician can explain how that differs from short-term delay and which approach fits your needs.
Side effects and what to expect
Most people tolerate a short course well, but as with any hormone treatment there can be temporary effects. These may include bloating, breast tenderness, headaches, nausea, mood changes, acne or a reduced sex drive. They usually settle once the course finishes and hormone levels return to normal. Some light spotting can occur, particularly if a dose is missed or the course runs close to its maximum length; this is not usually a cause for concern but is worth noting.
Because progestogens can slightly affect the risk of blood clots, it is important to seek urgent medical advice if you develop calf pain or swelling, chest pain, breathlessness, coughing up blood, or a sudden severe headache or vision changes while taking it. These effects are uncommon, especially over a short course, but knowing the warning signs is part of using the treatment safely. If side effects are troublesome, speak to a clinician rather than simply stopping without advice.
Period delay compared with the contraceptive pill
People sometimes ask whether they should use a short course of period delay tablets or manage their cycle with the contraceptive pill. They work differently and suit different needs. A short progestogen course is designed purely to postpone one expected period for a specific event, then let your natural cycle resume; it does not provide contraception.
If you already take, or are considering, hormonal contraception, there may be ways to adjust when a period arrives as part of that method, for example by running certain pill packs together under guidance rather than taking the usual break. This can be convenient if you want ongoing contraception and cycle control together. The best choice depends on whether you need contraception, how predictable your cycle is, and your medical history, so it is worth discussing both approaches with a clinician so you can weigh up which fits your situation.
Getting a clinical review
Because period delay is prescription-only, it starts with a short, discreet consultation. A clinician reviews your medical history, current medicines and the dates you want to cover, then confirms whether the treatment is suitable and explains exactly how to time it. This keeps the approach safe and tailored to your plans, and gives you the chance to ask questions before you start.
Planning ahead helps, as the tablets need to be started before your period is due; leaving it until the last minute can mean the delay is less reliable. If period delay is not right for you, a clinician can talk through alternatives, including hormonal contraception that can also be used to manage when periods happen. The aim is a simple, reliable plan for your specific occasion, with support available if anything is unclear.
Frequently asked questions
How long before my period should I start the tablets?
Period delay tablets are usually started around three days before your period is expected. Starting too late can allow bleeding to break through, so it helps to plan around your exact dates.
How long can I delay my period for?
A short course can typically postpone a period for up to around 17 days, though the prescriber will advise the safe maximum for you. It is intended for occasional, planned use rather than long-term cycle control.
When will my period come back after stopping?
Once you stop the tablets, hormone levels fall and your period usually returns within two to three days. Your natural cycle then continues as normal.
Does period delay work as contraception?
No. Period delay tablets such as norethisterone at these doses are not a reliable contraceptive. If you also need contraception, speak to a clinician about a method that can manage your cycle and prevent pregnancy.
Is period delay safe for everyone?
Not everyone. People with a history of blood clots, certain heart, liver or hormone-sensitive conditions, or unexplained bleeding may need an alternative. A clinician checks your history before prescribing.