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How effective is the morning after pill?

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How effective is the morning after pill?

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Dr Louisa Draper

"The morning after pill does not prevent pregnancy when you have sex after taking it. It is important that you use contraception the next time you have sex." - Dr Louisa Draper
Dr Louisa Draper

"The morning after pill does not prevent pregnancy when you have sex after taking it. It is important that you use contraception the next time you have sex."

Dr Louisa Draper

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The morning after pill prevents pregnancy after unprotected sex. How effective is it and what can reduce its effectiveness? Find out how to use it and how to avoid getting pregnant.

Contents

How long is the morning after pill effective for?

The two most common emergency contraceptive pills are Levonelle and Ellaone. The time frame within which they work differs:

Levonelle

Needs to be taken within 72 hours of sex. 

Its effectiveness decreases with time. Levonelle is: 

  • 95% effective if taken within 24 hours of sex
  • 85% if taken between 25 - 48 hours
  • 58% if taken between 48- 72 hours

Ellaone 

Ellaone needs to be taken within 120 hours (5 days) of sex. 

It is 95% effective if taken between 48 and 120 hours after sex.

The morning after pill is less reliable than the contraceptive pill or the condom. You should only take it in emergencies and use contraception every time you have sex. 

There are a number of factors which can reduce its effectiveness.

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What can make the morning after pill less effective?

There are certain things which can make the morning after pill less likely to work, such as certain medical conditions and medications:

Vomiting: You may experience nausea and vomiting as morning after pill side effects. If you vomit soon after taking the pill then there is a high chance that it won’t have been absorbed by your body. In this case, speak to a doctor. You may need to take another morning after pill to prevent pregnancy.

Other medications: Some medications can stop the morning after pill from working. This includes the following medications and remedies:

  • St John's Wort
  • HIV drugs such as Ritonavir or immune system suppressants
  • TB treating drugs such as Rifabutin
  • Barbiturates and other medications used to prevent seizures

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Does my weight affect the effectiveness of the morning after pill?

There is some evidence that the morning after pill may be slightly less likely to work in women with a high Body Mass Index (BMI). However, evidence is inconclusive and further research is required to determine whether weight affects the effectiveness of the morning after pill.

Women with a high BMI can use either morning after pill and they do not need to take a higher dose.

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Can you get pregnant after taking the morning after pill?

As with most contraceptives, there remains a risk that you could become pregnant. However, if you take the morning after pill within the correct time frame, this risk is small. In order to reduce your risk of pregnancy you should take the pill as soon after sex as possible.

It is not unusual for the morning after pill to affect your periods. You may find that your next period is lighter or late. If you miss your next period or subsequent periods are very light, you should visit a doctor to check whether you are pregnant.

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Can you have unprotected sex after taking the morning after pill?

The morning after pill does not prevent pregnancy when you have sex after taking it. It is important that you use contraception the next time you have sex.

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Who can take it?

The morning after pill is not suitable for everyone. If you suffer from any of the following, you may be advised not to take it:

  • severe liver disease
  • porphyria
  • Crohn’s disease
  • a stomach condition or a condition of the digestive system

You should also speak to a doctor before taking the morning after pill if you have any hormone issues or allergies. 

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Top tips for taking the morning after pill

1. The sooner you take the morning after pill, the better.

Don’t leave any more time than necessary between having unprotected sex and taking the morning after pill. The sooner you take it, the more likely it is to be effective.

2. If you have diarrhoea or vomit after taking it, consult a doctor.

If you are sick or have severe diarrhoea after taking the morning after pill, there is a risk that it won’t work. If this happens, you need to consult a doctor as soon as possible to check whether you need to take a second pill.

3. Make sure you mention any medication you are taking to your pharmacist or doctor.

Certain medications and remedies can stop the morning after pill from working. Before you take the morning after pill, inform your prescribing doctor or your pharmacist of any medication you have recently taken.

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