How effective is the morning after pill?

by | Babies and Pregnancy, Sexual Health

Your emergency contraceptive questions, answered

Emergency hormonal contraception is sometimes referred to as ‘the morning after pill’, although this can cause confusion since it should be taken as soon as possible after unprotected sex, not necessarily in the morning. It is also known as the emergency contraceptive pill (ECP).

Emergency contraceptive pills are one of the most popular emergency contraceptions available. They work by delaying the release of an egg, which can bebe crucial if there are sperm present because sperm can still fertilise an egg for many hours and even days after intercourse. The average survival is 2 to 3 days although some sperm can survive for 5 to 7 days. Research has found the morning after pill, if taken within the optimum window, can be 75 – 85% effective1-2

A copper intra-uterine device (IUD) is another form of emergency contraception.

Emergency contraceptive pill (ECP)

The emergency contraceptive pills commonly used in Australia include:

  • a progestogen called levonorgestrel (brand names include Postinor-1, Postinor-2, Postrelle -1, Postella-1, NorLevo, NorLevo-1, Levonelle-1 and Levonelle-2); or
  • ulipristal acetate (brand names include EllaOne).

These pills are more effective and cause less side effects than an older method of emergency contraception (known as the Yuzpe method), which involves taking 2 doses of combined oral contraceptive pills (which contain oestrogen and progestogen).

Emergency contraceptive pills can be used more than once to avoid unintended pregnancies. ECP does not cause abortion (termination) or affect future fertility.

There is some evidence to suggest that emergency contraceptive pills may not be as effective in preventing pregnancy in women who are overweight or obese. However, emergency contraception is still recommended for women who are overweight and wish to avoid pregnancy after unprotected sex.


Levonorgestrel is a progestogen – a type of synthetic progesterone. Levonorgestrel is available from the chemist without a prescription.

It has been estimated that levonorgestrel will prevent 85 per cent of pregnancies if taken within 72 hours of unprotected sex. The sooner you take the pill, the more likely it is to be effective.

Depending on the particular brand used, you will need to take a single dose of levonorgestrel as soon as possible after unprotected sex; or one dose as soon as possible and a second dose exactly 12 hours later. Your doctor or pharmacist will explain how you should take the emergency contraceptive pill.

You should let your doctor or pharmacist know if you are taking any other medicines, as some medicines can interfere with levonorgestrel, reducing its effectiveness. A larger dose may be needed in some cases.

Side effects of levonorgestrel can include: nausea, tender breasts and headaches. Some women experience irregular menstrual bleeding. Many women report no side effects.

If you vomit within 2 hours of taking the levonorgestrel emergency contraceptive pill, you should contact your pharmacist about whether you need to take another tablet.


Ulipristal mainly works by delaying or preventing ovulation. Ulipristal (brand name EllaOne) is effective if taken within 5 days of unprotected sex (compared with levonorgestrel, which is usually effective up to about 3 days).

Ulipristal has been found to be very effective in preventing pregnancy, especially if taken within 72 hours of having sex. Ulipristal is only available on prescription.

Ulipristal is not recommended for women who are breast feeding. Your doctor will also want to make sure that you are not already pregnant before you take ulipristal, as the effects on the developing baby are not known.

Side effects of ulipristal can include: nausea, headaches and abdominal pain and period pain.

If you vomit within 3 hours of taking the ulipristal emergency contraceptive pill, you should contact your pharmacist about whether you need to take another tablet.

It’s important not to start or resume taking some types of oral contraceptive pill within 5 days of taking ulipristal, as it can reduce the effectiveness of ulipristal. Use a barrier method of contraception (such as condoms) until your next period.

When you may need emergency contraception

Emergency contraception may be needed if you have had sex and the condom broke, or your diaphragm dislodged, or you missed taking the pill or had sex using no contraception at all. Emergency contraception can also be used to prevent pregnancy after a woman has been forced to have sex against her will (raped).

How long can you wait before getting emergency contraception?

Emergency contraception should be used as soon as possible after having unprotected sex. The emergency contraceptive pill can be effective 3 to 5 days after unprotected sex, depending on the type of pill used. A copper IUD is effective in preventing pregnancy up to 5 days after unprotected sex.

Where to get emergency contraception

Most doctors and pharmacists are familiar with providing emergency contraception, but if not, your family planning clinic or women’s health centre should be able to help you. Some emergency contraceptive pills are available from pharmacists without a prescription.

How does emergency contraception work?

In the normal course of events when a woman becomes pregnant, one of her ovaries releases an egg (ovulation) which is fertilised by sperm swimming up the fallopian tubes. The fertilised egg then passes down the fallopian tube into the uterus, where it embeds itself into the lining of the uterus.

Emergency contraception works by:

  • delaying or preventing the release of the egg (ovulation);
  • stopping the sperm from fertilising the egg; or
  • preventing a fertilised egg from implanting in the lining of the uterus (womb).

It is possible for sex taking place 5 to 7 days before ovulation to result in pregnancy and also sex taking place a day or so after ovulation to result in pregnancy (the egg is only viable for up to 24 hours after its release from the ovary).

Emergency contraception should only be used if a single act of unprotected sex has occurred since your last period. If there has been more than one act the doctor has to rule out the possibility of a pre-existing pregnancy. The use of emergency contraception is ineffective if implantation has already occurred. Also, some types of emergency contraception might do some harm if you are already pregnant.

Other forms of emergency contraception: Copper IUDs

The copper IUD method of emergency contraception is more than 99 per cent effective in preventing pregnancy when inserted within 5 days of unprotected sex.

Copper IUDs work by changing conditions in the uterus, affecting the movement of the sperm and egg, as well as reducing their viability. The IUD also changes the lining of the uterus, making it less suitable for a pregnancy.

A copper IUD (such as Load 375, TT380 Standard Intrauterine Device and TT380 Short Intrauterine Device) may be inserted by your doctor or at the family planning clinic within 5 days of unprotected intercourse. (In some cases, an IUD can be inserted up to 5 days after the earliest estimated day of ovulation if intercourse took place more than 5 days beforehand.)

The main advantage of using an IUD is that it offers ongoing contraception. However, IUDs are not particularly suitable for young women who have not had children, and they do not protect against sexually transmitted diseases . Copper IUDs are also not suitable for some women, including those with endometriosis. Your doctor will be able to assess whether an IUD is suitable for you.

Side effects of copper IUDs may include: heavy periods, period pain and intermittent spotting.

When to see the doctor

You should see your doctor if you are concerned that the emergency contraception has not been effective and you think you may be pregnant, or if you are concerned about sexually transmitted infections (STIs).

See the doctor if:

  • Your next period is different from usual (especially if it is shorter in duration or the bleeding is lighter).
  • Your period is more than a week late.
  • You experience severe, sudden pain in your pelvis or lower abdomen. (Sudden pain can be due to an ectopic pregnancy – a rare but serious condition where a pregnancy implants outside the uterus (womb), often in one of the fallopian tubes.)

As emergency contraception is not 100 per cent effective, you should take a pregnancy test if you have any symptoms that suggest you may be pregnant.

Ongoing contraception

If you had a copper IUD inserted for emergency contraception, you can continue to use the IUD as an effective, ongoing method of contraception.

The emergency contraception pill (ECP) does not provide ongoing (long-term) contraception. Another method of contraception is recommended for ongoing protection against pregnancy – talk to your doctor or family planning clinic about which method would be most suitable for you.

Using condoms is the best way to protect yourself from sexually transmitted infections (STIs).


[1] Contraception – emergency contraception – Better Health Victoria [Accessed 5 July 2023] Available from: (

[2] Emergency Contraception: “Morning After Pill” Yale Health. [Accessed 5 July, 2023] Available from: