Emergency Contraceptive Pills

Emergency contraceptive pills (ECPs) are a type of oral contraceptive that can be taken after intercourse to help prevent a pregnancy from occurring. While they are also known as the Morning After Pill, the name is somewhat inaccurate since ECPs can be taken up to 120 hours after you have unprotected vaginal sex.

How They Work

Like the birth control pill, ECPs are made up of either estrogen and progesterone or just progestin. However, the amount of hormones found in ECPs is significantly higher than in regular birth control pills.

Originally brought onto the market in the 1960s in order to prevent pregnancies in rape victims, ECPs are used as an emergency back up for women who have had unprotected sex or their contraception failed (i.e. the condom broke). They are not as effective as other forms of regular birth control.

Emergency contraceptive pills help to prevent a pregnancy in three ways:

  1. If your ovaries have not yet released an egg, ECPs can suppress ovulation
  2. If an egg has been released, ECPs can alter the movement of the ovum or embryo thereby preventing pregnancy from occurring
  3. If fertilization has occurred, ECPs can alter the lining of the uterus thereby preventing implantation from occurring

Most ECPs require you to take two doses: one within 120 hours of having unprotected sex and another 12 hours after the first dose. Taking an ECP will not offer you protection from pregnancy for the rest of your cycle. Therefore, it is necessary to use another form of birth control, such as a contraceptive sponge, until you get your next period.

If an egg has already been fertilized and implanted into the uterus, ECPs will not cause an end to the pregnancy. Additionally, ECPs cannot prevent an etopic pregnancy. An etopic pregnancy is one that occurs outside of the uterus and requires immediate medical attention.

Side Effects

There are a variety of side effects that women may experience when they take ECPs. These include:

  • Nausea and vomiting (effects may be reduced in women who take a progestin-only ECP)
  • Tender breasts
  • Dizziness
  • Irregular bleeding
  • Headaches

You may also find that your next period is heavier or lighter than usual and that it comes earlier or later than normal. Moreover, ECPs offer no protection against sexually transmitted diseases. It may be necessary for you to get tested for STDs if you think you’re at risk.

Getting Them and Effectiveness

ECPs used to be available through prescription only. However, nowadays the laws vary from state to state and from province to province. Depending on where you live, you may be able to get ECPs through a sexual health center or directly from a pharmacist as well as from your doctor.

In other places, it is still necessary to get a prescription for ECPs. In some cases you may be required to sign an informed consent contract. This may stipulate that you are aware of the associated health risks and will consider abortion if the ECP does not work.

ECPs must be taken within 120 hours of having unprotected intercourse in order to work. The sooner the ECP is taken, the more effective it will be. Combined estrogen and progesterone ECPs have been found, on average, to be 75% effective when taken with 72 hours of unprotected sex. Progestin-only ECPs have been found to be as much as 89% effective when taken within 72 hours of unprotected sex.


If you do not wish to use ECPs but have had unprotected sex or your regular birth control methods failed and you want to prevent a possible pregnancy, then you may decide to use one of two other types of emergency contraception. One option is to insert two applications of spermicide immediately after intercourse. This may prevent a pregnancy from occurring by killing off sperm. However, this is not a reliable method of emergency contraception.

The other is to have a copper IUD inserted up to five days after unprotected sex. The IUD inhibits pregnancy by preventing sperm from fertilizing an egg. It also changes the lining of the uterus and stops implantation from occurring.

While this method of emergency contraception has been shown to be as much as 99% effective, the IUD is not suitable for every woman, especially those who are at risk of having an STD, and there can be more side effects associated with its use. Discuss the advantages and disadvantages of this form of emergency contraception with your health care provider.

Find out more about the benefits of the morning after pill in our birth control forum.

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