How emergency contraceptives work

How do emergency contraceptives work?

Sperm cells can stay alive in your body up to 5 days after unprotected sex. So, if you ovulate within 5 days of having unprotected sex, then a sperm cell can fertilise the egg that is released during that ovulation.

You can get pregnant if you have sex 5 days before the day you ovulate.

  • The emergency contraceptive pills (levonorgestrel, ulpristal acetate) act by delaying or preventing ovulation. They also thicken the cervical mucus so as to prevent the sperm from fertilising the egg.
  • The combined oral contraceptive pills act by inhibiting ovulation.
  • And the intrauterine device (which in this case is usually copper T) prevents pregnancy by changing the sperm and egg chemically, thereby preventing fertilisation.

NOTE that ovulation is the process that releases the egg into the woman’s reproductive tract. It is when the egg is released that sperm (which has been ejaculated into the woman’s reproductive tract through her vagina) can fertilise it and ultimately lead to a pregnancy. So, if ovulation does not occur, pregnancy cannot occur. Also, if ovulation does not occur when the sperm cells are alive in the woman’s reproductive tract, then pregnancy will not occur.


When taking emergency contraceptive pills:

  • Levonorgestrel can be taken in one dose (1.5mg), or in two doses 12 hours apart (0.75mg each). These should be taken within 5 days of unprotected sexual intercourse. It is even better if they are taken within 3 days of unprotected sexual intercourse. Taking it earlier increases the chances of its effectiveness.
  • Ulipristal acetate is taken in one dose (30mg) within 5 days of unprotected sexual intercourse.
  • Combined oral contraceptive pills (Yuzpe method) are taken in 2 doses 12 hour apart. They should be taken within 5 days of unprotected sexual intercourse; but preferably within 3 days. Each of the two doses taken should contain progesterone (0.50-0.60 mg of levonorgestrel or 1.0-1.2mg of norgestrel) and estrogen (0.10-0.12 ethinyl estradiol).
  • For the copper intrauterine device, go to the hospital and ask the doctor to insert the device into your womb within 5 days of unprotected sexual intercourse.


Before using any form of emergency contraception:

  • First of all, do a pregnancy test to be sure that you are not pregnant. It is possible that you were pregnant, before the episode of unprotected intercourse that you want to use emergency contraceptives for. Because if you are already pregnant, then there is no need for the emergency contraceptives.
  • It is also important to let your doctor know if you have high blood pressure. This will help him or her to counsel you on the emergency contraceptive that is most suitable for you.
  • Also, let the doctor know if you are on any other medications. Because some medications react with the ‘morning after’ pills and make them not to function. And then, you might get pregnant.
  • It is also important to tell the doctor if you suffered from breast cancer, heart disease, liver disease or stroke (at that time or in the past).
  • Be sure to do another pregnancy test about 3 weeks after the episode of unprotected sexual intercourse to make sure that the emergency contraception worked.


Some more instructions:

  • Don’t take more than one brand of emergency contraceptive pill at the same time. They can both cancel out each other’s effect so that none of them would end up acting to prevent you from getting pregnant. Taking 2 different brands together will not increase the chances of preventing pregnancy.
  • Take the prescribed dose. Don’t take an overdose because you think that will make it more effective. All you will do is increase the side effects that you will have from the pills.
  • If you vomit 1 -2 hours after taking the emergency contraceptive pills, you should go see your doctor as soon as possible. This is because you may need to take another dose, as it is likely that you vomited the pills.
  • If you have any serious reactions or side effects from taking the pills, then go see your doctor immediately. Serious side effects from the emergency contraceptives is not common, so don’t be alarmed or afraid to use them.


Somso Kizor enjoys words. She loves reading good books and writing - amongst other things. Somso is passionate about educating people about their health; as this would reduce the burden of diseases and deaths (hence, suffering) all over the world. Let's not forget the popular saying that goes "health is wealth." For more details, send an email to


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