Emergency contraceptive pill

The emergency contraceptive pill, also known as the morning-after pill or post-coital pill, can be used by a woman to prevent pregnancy after having unprotected sex.

It can also be used if another method of contraception has failed; for example, if a condom splits or if you have missed contraceptive pills.

The emergency contraceptive pill can be used up to five days (120 hours) after having unprotected sex. However, the sooner it is taken, the more likely it will prevent pregnancy.

It can be taken more than once during your menstrual cycle, but does not protect you against pregnancy during the rest of your menstrual cycle and is not intended to be a regular form of contraception. Using the emergency contraceptive pill repeatedly can severely disrupt your natural menstrual cycle.

The emergency contraceptive pill does not protect against sexually transmitted infections.

How effective is it?

The effectiveness of the emergency contraceptive pill depends on how soon you take it after sex. Taking it within 12 hours of having sex gives the best chance of preventing a pregnancy.

The emergency contraceptive pill is:

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

How the emergency contraceptive pill works

The emergency contraceptive pill prevents the ovaries releasing an egg (ovulation). It also:

• thickens the mucus in the neck of the womb, so it is harder for sperm to penetrate into the womb and reach an egg
• thins the lining of the womb, so there is less chance of a fertilised egg implanting into the womb and being able to grow

Types of emergency contraceptive pill

There are currently two brands of emergency contraceptive pill available in the UK:

• Levonelle is the most commonly used emergency contraceptive pill. It can be taken up to three days (72 hours) after having unprotected sex and is available free of charge from most  local pharmacies.
• ellaOne is a newer type of emergency contraceptive pill that can be taken up to five days (120 hours) after having unprotected sex. It is only available on prescription and only recommended in women over the age of 18.

Other emergency contraception

The copper intrauterine device (IUD) is another method of emergency contraception. This prevents pregnancy if it is fitted within five days of having unprotected sex. For more information, see the Health A-Z topic on the intrauterine device