How effective is the morning after pill?

Dr. Babak Ashrafi

Medically reviewed by

Dr Babak Ashrafi

Last reviewed: 23 May 2022

The morning after pill is a type of emergency contraception that you can take after unprotected sex to prevent an unwanted pregnancy. There are 2 types of morning after pills available, EllaOne and Levonelle.

Unprotected sex happens when you’ve had sex without a condom, but it can also happen if the condom splits or if you forget to take your birth control pills.

Contents
How effective is the morning after pill?
 

Key takeaways

  • There are 2 types of morning after pills available, EllaOne and Levonelle.

  • EllaOne and Levonelle work to delay ovulation.

  • Both types of morning after pills need to be taken before ovulation.

  • EllaOne is 99% effective in preventing pregnancy when taken within 24 hours of having unprotected sex.

  • Levonelle is around 98% effective in preventing pregnancy if you take it within 24 hours of having unprotected sex.

EllaOne effectiveness

EllaOne is 99% effective in preventing pregnancy when taken within 24 hours of having unprotected sex. EllaOne remains effective if you take it up to 120 hours (5 days) after unprotected sex. The contraceptive effect is reduced after the first 24 hours, so it’s best to take the pill as soon as possible.

EllaOne contains the active ingredient ulipristal acetate. Ulipristal acetate delays ovulation by binding to progesterone receptors in your body. This stops ovulation from occurring by preventing an increase in luteinising hormone (LH). The LH surge triggers ovulation (the release of an egg) in your normal menstrual cycle.

The effectiveness of EllaOne can change if you’re taking any other medications, including:

  • epilepsy treatment, such as carbamazepine, phenytoin or phenobarbital
  • treatment for tuberculosis, such as rifampicin
  • HIV treatment, including ritonavir
  • antifungal medications, such as griseofulvin
  • St John’s wort, a herbal remedy used to treat low moods

Speak to a pharmacist or doctor before taking EllaOne if you’re taking any of these medications. They may advise an alternative method of emergency contraception.

Levonelle effectiveness

Levonelle is around 98% effective in preventing pregnancy if you take it within 24 hours of having unprotected sex. You can take Levonelle up to 72 hours (3 days) after unprotected sex but its effectiveness will decrease the longer you delay taking it.

Levonelle works by preventing ovulation. Levonelle contains levonorgestrel, a synthetic progestogen hormone. Synthetic progestins mimic how natural progesterone works in your body.

Levonelle contains 1500 micrograms of levonorgestrel, which is a high dose of progestogen. Taking a high dose suppresses your ovaries from ovulating and releasing an egg.

Like EllaOne, certain medications can change the effectiveness of Levonelle. Speak to a pharmacist or doctor if you are taking any regular medications or over the counter products.

If you have a high body mass index (BMI), your doctor may suggest taking 2 tablets of Levonelle to ensure it is effective.

Levonorgestrel effectiveness

Generic levonorgestrel is as effective as branded Levonelle as it contains the same amount of active ingredient (1500 micrograms of levonorgestrel) in each tablet. You can request generic levonorgestrel, Levonelle or EllaOne from ZAVA.

Which emergency contraception is the most effective?

EllaOne is more effective than Levonelle. Both types of morning after pills need to be taken before ovulation, so it’s a good idea to get to know your menstrual cycle. If you use emergency contraception after ovulation, it will not be effective.

Ovulation is triggered by a process called the LH surge. An increase in luteinising hormone leads to the release of an egg from an ovary. Both EllaOne and Levonelle should be taken before the LH surge.

EllaOne is effective even when the levels of LH start to rise (such as just before the peak of the LH surge). This means it’s effective for longer after unprotected sex compared to Levonelle.

If you want to prevent pregnancy, try to use emergency contraception as soon as possible. This is usually within the first 24 hours of having unprotected sex.

How long is the morning after pill effective?

Each morning after pill will only work for one instance of unprotected sex. This means you can still get pregnant if you have unprotected sex after you’ve taken the morning after pill.

The morning after pill does not affect your fertility. After you’ve taken the morning after pill, you should use a condom until you have your next period. You may have to do this even if you take birth control pills, depending on your daily contraceptive pill.

Both EllaOne and Levonelle can cause mild side effects. These side effects should not affect the way the pill works. However, if you vomit within 2 to 3 hours of taking EllaOne or Levonelle, speak to your pharmacist or sexual health clinic. You may need to take another tablet.

How effective is the morning after pill when ovulating?

The morning after pill is not effective when you’re ovulating. Both EllaOne and Levonelle work to delay ovulation. Once ovulation has begun, they will no longer work.

Ovulation usually occurs around 2 weeks after your period, but everyone’s body is different. You can track your menstrual cycle using an app or calendar to get a better idea of when you are ovulating.

It can be difficult to tell when you are ovulating, but here are some signs to look out for:

  • cervical mucus becomes slippery or wetter
  • a slight increase in your body temperature
  • mild pelvic pain that happens on one side

Another form of emergency contraception is the copper IUD (intrauterine device). The copper IUD is 99% effective when it’s fitted as soon as possible. You’ll need to get it fitted within 5 days of having unprotected sex.

You may be able to get the copper IUD fitted up to 5 days after the earliest point you could have ovulated. You can also use the copper IUD as regular contraception once it’s been fitted. Speak to a doctor or sexual health clinic for more information.

There are 2 types of morning after pills available, EllaOne and Levonelle.

You may need to take the morning after pill if you've had unprotected sex. Unprotected sex happens when you’ve had sex without a condom, but it can also happen if the condom splits or if you forget to take your birth control pills.

Both EllaOne and Levonelle are available from most pharmacies. You can also request the morning after pill from ZAVA without needing an appointment.

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Medically reviewed by:
Dr Babak Ashrafi Clinical Lead for Service Expansion

Babak studied medicine at King’s College London and graduated in 2003, having also gained a bachelor’s degree in Physiology during his time there. He completed his general practice (GP) training in East London, where he worked for a number of years as a partner at a large inner-city GP practice. He completed the Royal College of GPs membership exam in 2007.

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Last reviewed: 23 May 2022


You might need emergency contraception if you’ve recently had unprotected sex and want to reduce your risk of getting pregnant. ZAVA offers a morning after pill service, which includes a variety of options.




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