Does emergency contraception affect your period?

Taking emergency contraception can feel stressful, especially if your next period doesn’t arrive when you expect it to. It’s common to feel unsure about what’s normal, what might be a side effect and when you should take a pregnancy test.

In this guide, we explain how emergency contraception can affect your period, why your bleeding may be different and when to seek medical advice.

How does emergency contraception affect your period?

When using emergency contraception, there is always a chance that your next period will be a little different to normal. That’s especially true if you take an emergency contraceptive pill such as levonorgestrel or ulipristal acetate, which interact with your hormones. 

These medicines work mainly by delaying or preventing ovulation, which can temporarily shift the timing of your menstrual cycle. As a result, your next period may arrive earlier or later than expected. 

You may also notice that your period feels different. This could include:

• Your flow being heavier or lighter than normal
• Experiencing stronger cramps or period pain
• Spotting or irregular bleeding before your next period.

These changes can feel unsettling, but they’re usually short term and should settle as your cycle returns to normal.

The copper IUD, sometimes called the copper coil, can also be used as emergency contraception. It doesn’t contain hormones, but it can cause some changes, including:

• Bleeding between periods
• Periods feeling heavier, more painful or longer
• Cramps for a few days after the IUD is fitted.

There is also a small chance of developing recurrent thrush - you should speak to a GP if you notice anything amiss. Period changes triggered by the copper IUD usually resolve in the first three to six months.

Important! A late or unusual period doesn’t always mean you’re pregnant, but it’s important to check. Take a pregnancy test if your period is more than 7 days late, much lighter than usual or if you’re worried emergency contraception may not have worked.

You can also take a pregnancy test at any point from the first day of a missed period. If you’re not sure when to expect your period, test at least 21 days after you had unprotected sex.

When should you be concerned about changes to your period after emergency contraception?

Most period changes after taking emergency contraception are temporary and aren’t usually a sign that something is wrong. However, it’s a good idea to seek advice if your period is more than 7 days late, as you may need to take a pregnancy test for peace of mind.

You should also speak to a pharmacist, doctor or nurse if your bleeding is very heavy, lasts much longer than usual or you have severe lower tummy pain, especially if the pain is on one side. These symptoms don’t always mean there’s a serious problem, but they should be checked.

If you vomit within 2 hours of taking the emergency contraceptive pill, ask for advice, as you may need another dose.

Can emergency contraception cause infertility?

No, emergency contraception doesn’t cause infertility. This is a common worry, but there’s no evidence that taking the emergency contraceptive pill affects your ability to get pregnant in the future.

Emergency contraceptive pills, such as levonorgestrel or ulipristal acetate, work mainly by delaying or preventing ovulation. This means they help to reduce the chance of pregnancy from a single instance of recent unprotected sex, but they don’t provide any kind of ongoing protection.

The copper IUD can be used as an ongoing contraceptive method, if you choose. It can be removed by a trained healthcare professional when you no longer want it, at which point your fertility returns to previous levels straight away, with no increased risk of impaired fertility.

Changes to your period after emergency contraception can feel unsettling, but they’re usually short lived and nothing to panic about. The most important thing is to take a pregnancy test if your period is late and ask a healthcare professional for support if something doesn’t feel right.