The morning-after pill

9th December, 2022 • 11 min read

Also known as the emergency contraceptive pill, the morning-after pill can prevent pregnancy if you take it after you’ve had unprotected sex or your birth control (contraception) has failed – for example, if a condom has split or you’ve missed a pill.

There are 2 types, usually known by their brand names. One contains levonorgestrel – often called Plan B (or Levonelle in the UK) – and the other contains ulipristal acetate – called ella (or ellaOne in the UK).

If you’re here for information about emergency contraception, it may be because you’re worried that you’re at risk of an unwanted pregnancy. So read on for the facts about how the morning-after pill works, where to get it, and when and how to use it – so you can act quickly if you need to.

Why do women choose emergency contraception?

“Lots of women need to use emergency

at some point in their lives, because contraception can go wrong even if you’re being careful,” says Dr Ann Nainan, family doctor and Healthily expert. “Whatever your situation, you’ll be reassured to know that, when used correctly, the morning-after pill can be very effective at preventing pregnancy.”

Common reasons you might choose to take the morning-after pill include if:

  • your contraception went wrong – for example, a condom split, or you forgot to take the pill and only realized later
  • you’ve had sex without using contraception, or using the
    pull-out (withdrawal) method
  • because of a traumatic situation – such as sexual assault, or someone removing a condom during sex without your consent. If this has happened to you, go to your nearest emergency room, or call the
    National Sexual Assault Telephone Hotline
    in the US, or
    Rape Crisis
    in England and Wales. You may also want to report it to the police

How does the morning-after pill work?

The morning-after pill aims to stop or delay your ovaries from releasing an egg (

– which stops an egg being fertilized by any sperm that may be in your body.

To give the morning-after pill the best chance of working, you need to take it within 3 to 5 days of having unprotected sex. The sooner you take it, the better the chance of it working.

There are 2 types of pill, which work in slightly different ways:

  • Plan B One-Step (also called Take Action or My Way, and Levonelle in the UK) – these pills all contain levonorgestrel, a synthetic version of the hormone progesterone, which is made by your ovaries
  • ella (ellaOne in the UK) – this pill contains ulipristal acetate, which affects the way progesterone works

Is the morning-after pill an abortion pill?

Some people wonder if the morning-after pill is an abortion, but it works in a completely different way. It’s a type of birth control because it stops pregnancy from happening – it doesn’t work if you’re already pregnant.

Emergency contraception is legal in states where abortion is illegal – although some states have restrictions on its access and use.

The morning-after pill isn’t a regular contraceptive

Although it’s safe to take it, the morning-after pill hasn’t been approved for regular use, and it doesn’t work as well to prevent pregnancy as other

types of contraception

So it shouldn’t be treated as regular contraception.

Emergency contraception won’t protect against STIs

The morning-after pill doesn’t stop

sexually transmitted infections (STIs)
– so if you’ve had unprotected sex, or a condom has split or come off, you may be at risk. Visit a sexual health clinic if you’re concerned.

How effective is the morning-after pill?

Here’s what research says about effectiveness:

  • Plan B/Levonelle and other levonorgestrel morning-after pills prevent between 69% and 85% of pregnancies when taken within 3 days (72 hours) of unprotected sex
  • the sooner you take Plan B or a similar pill, the better it works (you can it take up to 5 days after unprotected sex, but it may be less effective)
  • it’s not effective if you take it after ovulation
  • ella/ellaOne can be more effective, and can prevent up to 85% of pregnancies when taken within 5 days (120 hours) of unprotected sex
  • again, it’s not effective after ovulation, so the sooner you take it the better
  • ella works better – and for longer after unprotected sex – because it’s still able to prevent ovulation even after the start of a rise in hormones that triggers the release of an egg
  • if you think you’re close to ovulation or you’re in the later half of your
    menstrual cycle
    , or you’re not sure, an
    intrauterine device (IUD)
    is a more effective type of emergency contraception

How long does the morning-after pill protect you for?

After taking the morning-after pill, you’ll usually ovulate later in your cycle than usual – so you could still get pregnant if you have unprotected sex later on in that cycle.

If you want to avoid pregnancy, talk to your doctor about starting regular birth control. And if you’ve used emergency contraception but haven’t had a

, take a
pregnancy test

Can you get pregnant in the future after taking the morning-after pill?

The morning-after pill won’t affect your fertility in the future, even if you take it several times. The reason doctors say you shouldn’t use it as birth control is because it’s less effective than regular contraception – not because it’s harmful.

Morning-after pill side effects

The morning-after pill is safe, and doesn’t cause serious side effects.

However, you may get the following mild side effects:

  • nausea, tummy ache or a headache – read more about this
  • period changes – your period may arrive earlier or later than usual, or be heavier, lighter or more painful. But you may not notice any difference at all

Which morning-after pill is right for me?

You might be wondering why you wouldn’t just take the most effective morning-after pill. But there are a few reasons why you might choose one type of emergency contraceptive pill over the other:

Convenience (where you can get it)

  • you can usually get Plan B/Levonelle from your local drugstore or pharmacy without a prescription (although a few US states have restrictions on access). You may need to ask the pharmacist to fetch it for you, but you
  • won’t need to show ID – and any gender can get it
  • in the US, you need a prescription for ella – although in some states you can get one from the
    Planned Parenthood Direct app
    or a pharmacist
  • in the UK, you can buy ellaOne from a pharmacy or online
  • if you can’t easily get ella and want to take the morning-after pill quickly, it may be more convenient to go to your local drugstore for Plan B or a similar pill


  • in the US, you may be able to get the morning-after pill for free if you have health insurance or Medicaid
  • in the UK, you can get either type of pill for free from your doctor, sexual health clinics and some NHS walk-in centers and pharmacies
  • if you need to pay for your emergency contraception and cost is an issue, a levonorgestrel type of morning-after pill is usually cheaper than ella

Timing (when you can take it)

  • Plan B needs to be taken within 3 days of unprotected sex, but you may not get emergency contraception within that time – if you’re on vacation or don’t decide you need it right away, for example
  • ella is effective within 5 days of unprotected sex, so you have a couple more days to take it
  • it’s important to take either type of pill before you ovulate – after that, they won’t work. But it’s often not possible to be sure when you’ve ovulated, and you can still take them at any time in your cycle (if you do get pregnant, they won’t affect a pregnancy)

Your weight

  • research shows that Plan B/Levonelle may not work as well if you weigh more than 165 lbs
  • if you weigh more than 165 lbs, experts advise you take ella or have an
    fitted instead

You’re breastfeeding

  • you shouldn’t breastfeed for one week after taking ella
  • there are no restrictions on using Plan B if you’re breastfeeding
    small amounts of hormones may get into breast milk, but this hasn’t been shown to cause any harm to a baby

You’re taking other medication

  • ella might not work if you’re taking certain medications – including omeprazole for
    , some medicines for
    , seizures and
    tuberculosis (TB)
    , some less commonly prescribed
    and the herbal remedy St John’s wort
  • you can still take Plan B/Levonelle with these medications, but you may need a higher dose

How to take the morning-after pill

The morning-after pill is straightforward to take – just remember:

  • take it as soon as possible after you’ve had unprotected sex or your contraception has failed – within 3 days for Plan B or 5 days for ella
  • the sooner you take it, the more effective it’s likely to be
  • if you throw up (vomit) within 2 hours of taking Plan B or 3 hours of taking ella, you’ll need to take another dose, or have an IUD fitted
  • if you’re concerned about feeling sick, you can get anti-nausea medicines from your pharmacist to prevent vomiting

Taking the morning-after pill with other contraception

Sometimes, you may need to take an emergency contraceptive pill when you’re already using regular birth control – if you missed a couple of pills in your pack or were late changing your contraceptive patch, for example.

You may need to use condoms for a while, to allow time for your regular contraception to start working again. It will depend on what you’re taking, so check with your healthcare provider.

When to see a doctor

You should do a pregnancy test or see a doctor if you’ve taken the morning-after pill and:

  • your next period is more than 7 days late
  • your next period is shorter or lighter than usual
  • you think you may be pregnant

Read about how to use a pregnancy test.

You should see a doctor if:

  • you’re concerned that you may be at risk of an STI – the morning-after pill doesn’t protect against these
  • you need to use emergency contraception repeatedly – while it’s safe to take the morning-after pill frequently, it’s not the most effective way of preventing pregnancy. Regular contraception is more reliable and convenient, and a healthcare professional can advise on what’s right for you

You should get emergency help if:

  • you have sudden pain in the lower part of your abdomen – this can be a sign of an
    ectopic pregnancy
    , where a fertilized egg implants outside the womb, and it’s a medical emergency

Your health questions answered

Can I get the morning-after pill in advance?

“Yes, it’s available to buy in advance for emergency situations – but remember it has a much higher risk of pregnancy than regular contraception,” says Dr Ann. “If you’re using condoms, having the morning-after pill as back-up might give you peace of mind, in case the condom splits or comes off. If you already have a supply, you can take it immediately, giving it the best chance of working well. But if preventing pregnancy is important for you, you might want to think about a more reliable method than condoms. Some women also like to take the morning-after pill with them on vacation, as it may be harder to access while away. You can pick up Plan B/Levonelle, or ask a healthcare professional for a prescription for ella/ellaOne.”

I took the morning-after pill and then had unprotected sex – will it work?

“No – emergency contraception helps to prevent pregnancy when you take it after you’ve had unprotected sex,” explains Dr Ann. “It doesn’t work as contraception. If you’ve had unprotected sex shortly after taking the morning-after pill, get advice from a doctor or pharmacist.”

Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.