Patient information from BMJ

Contraception: emergency contraception

Last published:Apr 25, 2022

Emergency contraception can usually prevent pregnancy if you use it within a few days of having unprotected sex. There are several kinds.

You can talk to your doctor or pharmacist about which method is most suitable for you, about contraception in general, and about how best to avoid emergency situations in future.

What is emergency contraception?

Whether it’s the pill, condoms, or other methods, contraception is usually something that you think about before you have sex.

But you use emergency contraception after you have sex. There are several reasons why women might need it, including if:

• another method of contraception has failed: for example, a condom has burst

• you missed a day taking your pill or started a new pack later (check with your pharmacist or doctor. You might still be protected with some types of pill)

• you are concerned that you didn’t use your regular contraception properly: for example, you forgot to replace a patch or a vaginal contraceptive ring in time (again, check with your pharmacist or doctor to see if you’re still protected), or

• you had unprotected sex for any reason.

None of the emergency contraception methods in this leaflet protect against HIV or other sexually transmitted infections (STIs).

If you need emergency contraception after unprotected sex with a new partner, you might want to think about being tested for STIs.

Different types of emergency contraception

There are several methods of emergency contraception:

• Special contraceptive pills that you take after having sex. These are also known as 'morning after' pills, although they usually still work even if you take them a few days after you have had sex.

  There are two kinds of morning after pill. They are both available to buy without prescription in many countries, including the UK. In some countries they are available for free from family planning clinics and other health centres.

• The copper intrauterine device (IUD).

The copper IUD

The copper IUD is the most effective method of emergency contraception and the one that many doctors recommend.

The copper intrauterine device, or IUD, is usually used as a long-term method of contraception. It is a small device that is fitted into your womb by a doctor or nurse. For more information on the copper IUD, see our leaflet Contraception: intrauterine devices (IUDs).

The copper IUD can also work as emergency contraception if you have one fitted up to five days after having unprotected sex. It works by stopping a fertilised egg from implanting into the womb.

It can cause side effects, including changes to your normal bleeding patterns, such as heavier bleeding.

Having a copper IUD fitted as emergency contraception usually means deciding that you want to use it as your regular method of contraception for some time to come.

The morning after pill

There are two types of morning after pill:

• One uses a type of hormone called a progestogen hormone. You might have heard of it by one of its brand names, although these vary by country. Two of its brand names are Levonelle and Plan B.

• The other uses a drug called ulipristal. It goes by various brand names, including Ella, Ellaone, Esmya, and Fibristal.

Morning after pills don’t work if a fertilised egg has already implanted in your womb and you are already pregnant. So they don’t cause an abortion or miscarriage.

The progestogen hormone morning after pill (Levonelle, Plan B) works by stopping your ovaries from releasing an egg (ovulation). It might also work by preventing a fertilised egg from implanting in the womb (uterus). If a fertilised egg doesn’t implant in this way, it can’t develop into a fetus.

This method of emergency contraception works best if you use it within three days after you have sex. It can sometimes work for up to five days. But the sooner you use it after you have sex, the more likely it is to work. 

It sometimes comes as a single pill, and sometimes as two pills, so that you take one pill right away and the other one 12 hours later.

The main side effects of this pill are:

• headaches

• irregular periods 

• painful menstrual cramps, and

• nausea. If you vomit within three hours of taking the pill, you might need to take another for it to work. Ask your pharmacist or check the information leaflet that comes with the pill. 

You can start using your regular contraception method immediately after using this pill. But you will need to use a barrier method as well, or to not have sex, for seven days. 

To make sure that the pill has worked, you should wait take a pregnancy test three weeks after the last time you had unprotected sex. 

The ulipristal morning after pill (Ella, Ellaone) works in a similar way to the progestogen hormone pill. But research suggests that it might work better than the progestogen pill.

The main side effects of this pill are similar to those of the hormonal morning after pill.

If your regular method of contraception is hormonal (such as the contraceptive pill or any other method that uses hormones) you will need to wait five days after using this pill before using your regular method again. 

As with the progestogen pill, you will need to take a pregnancy test after a few weeks to make sure it has worked.

Ulipristal is not suitable for women with severe asthma. 

Why contraception matters

The number of unplanned pregnancies tells us how important it is for sexually active people to think about contraception. For example:

• in the UK about 30 in 100 pregnancies are unplanned, and

• in the US about 50 in 100 pregnancies are unplanned.

This is not always bad news, of course. Just because a pregnancy is unplanned doesn’t mean it’s unwanted. 

But many unplanned pregnancies end in abortions, which can cause emotional distress, and can have physical health risks, such as infections.

Emergency contraception can be very effective at preventing pregnancy after unprotected sex, but it doesn’t always work. There are many other methods that give you greater control and peace of mind.

Whatever method you choose, planning and taking responsibility for contraception is vital if:

• you are a sexually active girl or woman who could become pregnant, and you do not wish to become pregnant

• you are a sexually active male having sex with females of childbearing age, and you wish to play a responsible part in avoiding an unwanted pregnancy

• you think that you might be at risk of HIV or other STIs (for example, if you have multiple sexual partners) and you want to use a method of contraception that protects against infection.

Very few methods of contraception are totally effective. But planning gives you the best chance of being in control of when and if you become pregnant.

Your doctor or practice nurse will be very happy to discuss contraception and family planning methods that best suit you.