How long does it take the morning after pill to work?

If you’ve had unprotected sex or your usual contraception didn’t go to plan, it’s completely understandable to want answers. The good news is that the emergency contraceptive can still work even if it’s been a couple of days since sex. But timing does matter, and the sooner you take it, the better chance it has of preventing pregnancy.

This depends on which type of day after pill you choose. In the UK, there are two main types of morning after pill, ulipristal acetate and levonorgestrel. 

Ulipristal acetate (ellaOne)

You can take ellaOne, which uses an active ingredient called ulipristal acetate, up to 120 hours (5 days) after having unprotected sex.

Levonorgestrel

You can take levonorgestrel for up to 72 hours (3 days) after unprotected sex. If it’s been longer than 3 days, levonorgestrel is unlikely to work.

Even though ulipristal acetate is effective for a longer window after unprotected sex, it’s still best to take it as soon as you can since ovulation times can be unpredictable. It’s not advisable to just wait and see if your period comes – taking it earlier is always more effective and gives a greater chance that it will work.

The morning after pill works by helping to delay or prevent ovulation, meaning your ovary doesn’t release an egg. If there’s no egg, sperm have nothing to fertilise, which helps prevent pregnancy.

But, it’s important to remember that the morning after pill doesn’t provide ongoing protection from pregnancy. So, if you have unprotected sex again, you still run the risk of pregnancy happening. That’s why it’s so important to use a method of contraception such as condoms or the daily contraceptive pill, or follow any advice about contraception that your pharmacist or doctor gives you.

Emergency contraceptive pills work by delaying ovulation, so if ovulation has already happened, it is no longer effective. Most women don’t know precisely when they ovulate, and it can vary depending on cycle length and a number of other factors. In fact, only a small percentage of women ovulate exactly 14 days after they start their period. This is true even for women whose cycles are usually 28 days long.

That’s why the sooner you take the morning after pill after you have unprotected sex, the better the chance it has of working effectively. Even if you’re unsure where you are in your cycle, it’s still worth seeking advice as soon as possible so you can choose the most suitable emergency contraception option for you.

If it’s been longer than 5 days since you had unprotected sex, morning after pills like ellaOne won’t be suitable to help prevent a pregnancy. This can feel scary, but there is still support available. 

You should visit a pharmacist, your GP or a sexual health clinic as soon as you can, so they can discuss your options.

No emergency contraception is 100% effective, but the day after pill can significantly reduce your risk of pregnancy happening.

How effective it is can depend on things such as:

• How soon you take it
• Where in your cycle you are
• Any medications you take
• Your weight or BMI
• If you’re sick after taking it

One thing to remember is that if you vomit within 3 hours of taking the morning after pill, you will need to take another tablet as soon as possible. If this happens, it’s important to speak to a pharmacist or other healthcare professional for advice.

Waiting to find out if the morning after pill has worked can be the hardest part emotionally, especially if you’re anxious or overthinking every little symptom.

It’s a good idea to take a pregnancy test if:

• Your period is more than a week late
• Your period feels unusual for you
• You have pregnancy symptoms
• You just want reassurance

Most healthcare professionals recommend taking a test around 3 weeks after unprotected sex.

If you think you need emergency contraception, it’s important to try not to panic. Many people need the morning after pill at some point in their lives, and seeking help quickly is crucial.

You can take levonorgestrel up to 3 days after having unprotected sex, while a morning after pill containing ulipristal acetate like ellaOne can be taken for up to 5 days after, but both are most effective when taken as soon as possible. Just because you can technically take ellaOne later, doesn’t mean you should.

You can get ellaOne for free from many pharmacies via the NHS Pharmacy Contraception Service, or you can buy it online.

And if it’s been longer than 5 days, don’t sit and panic alone. Speak to a healthcare professional who can talk you through your options without judgement. 

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