Emergency Contraception

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If you have unprotected sex but do not wish to become pregnant, you may need emergency contraception. This is the term used for contraception used AFTER you have already had sex. There are several options available, but they must be used within 3-5 days after the unprotected sex. There are two types of pills which have a good chance of preventing pregnancy, sometimes called the "morning after pill". Alternatively an intrauterine contraceptive device (IUCD) can be fitted, which is even more effective.

There are three types of emergency contraception now available to women. These are two types of pill, and the intrauterine contraceptive device (IUCD) - also called the coil. They are available from your GP practice, NHS walk-in centres, family planning organisations (like British Pregnancy Advisory Service or Brook) and pharmacies.

Emergency contraception can be used:

  • If you have had sex without using contraception.
  • If you have had sex, but there was a mistake with contraception. For example, a split condom or if you forgot to take your usual contraceptive pills.

This is a pill that contains levonorgestrel which is a progestogen hormone. There are several different ones available, but they all contain the same dose of levonorgestrel. You can get it free on prescription or you can buy it from pharmacies, without a prescription. The usual dose is one pill which contains 1.5 mg of levonorgestrel. (Some women need a higher dose if they are taking certain other medication - for example, women taking certain anti-epilepsy medicines.)

When do I take it and how does it work?

Take the pill as soon as possible after unprotected sex. The earlier you take the pill, the more effective it is. It should be taken within 72 hours (three days). It is thought to work mainly by preventing or delaying the release of an egg from your ovary, which normally happens each month (ovulation). It is not thought to cause an abortion, ie it does not have an effect if an embryo has already settled (implanted) into the womb (uterus).

How effective is the progestogen pill?

Although emergency contraception is effective, it is not as reliable as regular planned contraception. Therefore, it should only be used in emergencies. The progestogen pill becomes gradually less effective the more time elapses after having unprotected sex. However, there is a good chance of preventing pregnancy if it is taken up to 72 hours after unprotected sex.

It is difficult for scientists to work out exactly how effective it is. This is because after having unprotected sex on one occasion, only a few women would get pregnant. It is difficult to work out which women would not have got pregnant anyway and which pregnancies were actually prevented by taking the morning after pill. If 1,000 women had unprotected sex once, around 60 to 80 would become pregnant. If all those women had taken Levonelle®, only around 11 to 26 would have become pregnant.

It is sometimes used between 72 and 120 hours after unprotected sex but the chance of it working is much less if it is taken after 72 hours, particularly so after 96 hours (four days).

Are there any side-effects with the emergency progestogen pill?

Side-effects with the emergency progestogen pill are uncommon. However, some women feel sick for about 24 hours after taking the pill. Some women are actually sick (vomit.) This may be less likely to happen if the pill is taken with food.

If you vomit within two hours of taking the pill then either:

  • Take another pill as soon as possible. (You may need to get a further prescription, or buy another pill from the pharmacy. You may also wish to get a prescription for some antisickness tablets.)
  • OR a coil (IUCD) can be inserted (see below).

Other mild side-effects occur in some women for a short time, such as diarrhoea, dizziness and breast tenderness. There may be some change to your periods in the month after taking the pill. Your period may be early, or late, or you may get some erratic bleeding.

Who should not take the emergency progestogen pill?

Most women are able to take the emergency progestogen pill. However, it is not suitable for all women. For example, women with a rare condition called porphyria should not take it. Also women who have very severe liver disease, or very severe Crohn's disease may not be able to take it.

Several other medicines can interfere with the emergency progestogen pill, meaning it may not work as effectively. This includes:

Make sure the doctor, nurse or pharmacist prescribing you the emergency contraception pill knows about all the other pills you are taking.

If the pill did not work and you became pregnant, there is no evidence that taking the emergency progestogen pill is harmful to the baby.

Ulipristal acetate (brand name ellaOne®) is a type of emergency contraceptive pill that was launched in the UK in 2009. It is taken as one single tablet.

When do I take it and how does it work?

Take the pill as soon as possible after unprotected sex. The earlier you take the pill, the more effective it is. It can be taken up to 120 hours (five days) after having unprotected sex. It is a type of hormone which seems to work by stopping or delaying release of an egg (ovulation).

How effective is ulipristal acetate?

Although emergency contraception can be effective, it is not as reliable as regular planned contraception. Therefore, it should only be used in emergencies. It is most effective if you take the tablet as soon as you can, after having unprotected sex. The effectiveness decreases the longer you leave before taking the tablet.

It is difficult for scientists to work out exactly how effective it is. This is partly because it is a new pill, so there aren't too many studies. Also, after having unprotected sex on one occasion, only a few women would get pregnant. So it is difficult to work out which women would not have got pregnant anyway and which pregnancies were actually prevented by taking the morning after pill. If 1,000 women had unprotected sex once, around 60 to 80 would become pregnant. If all those women had taken ellaOne®, only around 9 to 18 would have become pregnant.

It looks as though ellaOne® may be very slightly more effective than Levonelle®, particularly when taken between 3-5 days after unprotected sex.

Who should not take ulipristal acetate?

Ulipristal acetate cannot be taken if there is any possibility that you might be pregnant. It also cannot be taken if you have certain liver diseases or have severe asthma. You should not breast-feed for one week after taking this tablet.

Some other medicines can interfere with ulipristal acetate, making it less effective. If you take one of these pills it may be better to use another form of emergency contraception. Medicines which may interfere with ulipristal acetate include:

Also, ulipristal acetate may interfere with the action of other contraceptive pills. If returning to other contraceptive pills after taking ulipristal acetate, you will need to use condoms or avoid having sex for a little while. How long this should be depends on the pill you are taking:

Always make sure the person prescribing you the emergency contraception pill knows about any other medication you are taking.

Are there any side-effects of ulipristal acetate?

Side-effects with the ulipristal acetate pill are uncommon. These can include headaches, feeling sick, tummy (abdominal) pains, dizziness and muscle pains. After taking it, your periods may be different for the next month. Your period may be earlier than expected, later than expected, or you may have some erratic bleeding.

If you are sick (vomit) within two hours of taking ulipristal acetate then you will need to take another tablet. You will need another prescription for this.

  • If you take the progestogen pill more than 72 hours or the ulipristal acetate pill more than 120 hours after unprotected sex.
  • If you are sick (vomit) within three hours of taking the pill and do not take a repeat dose.
  • If you also had unprotected sex at an earlier time since your last period.
  • If you have unprotected sex again after taking emergency contraception.

An alternative method of emergency contraception is to have an IUCD (often known as a coil) inserted by a doctor or nurse. This can be done up to five days after unprotected sex. It has the advantage of providing ongoing contraception and is also more effective than taking hormone tablets. Less than 1 woman in 100 would get pregnant after having the coil inserted for emergency contraception, meaning it is nearly 100% effective.

Most women can use the coil. Exceptions include those who have copper allergy, and those who have infections or cancer in their genital areas or womb (uterus).

See separate leaflet called Intrauterine Contraceptive Device (IUCD) for details.

  • Most women have their next period at about the usual time. Sometimes it is a few days earlier or later than expected. See a doctor or nurse if your next period is more than seven days late or if it is lighter than usual. A pregnancy test may be advised.
  • Your next menstrual cycle may also be shorter or longer than usual.
  • There is still a small risk of pregnancy even if you use an emergency contraceptive correctly.

You may want to discuss your regular contraceptive needs with a doctor or nurse. This may be best in a relaxed follow-up consultation.

See a doctor urgently if you have any lower tummy (abdominal) pain or abnormal bleeding in the 2-6 weeks following use of emergency contraception. These are the main symptoms of an ectopic pregnancy. This is rare, but it is best to be aware of the possibility as it is a serious condition. Also, do a pregnancy test or see a doctor if your next due period is more than seven days late. See your doctor if you have any other concerns or questions.

Further help & information

Original Author:
Dr Tim Kenny
Current Version:
Peer Reviewer:
Prof Cathy Jackson
Document ID:
4539 (v45)
Last Checked:
19/01/2015
Next Review:
18/01/2018
The Information Standard - certified member
See also: Emergency Contraception written for professionals

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