Emergency Birth Control (Morning-After Pill)

What is emergency birth control?

Emergency birth control, also called the morning-after pill, is a medicine that can prevent pregnancy if a woman takes it within 72 hours of having intercourse. It may be used when you have had unprotected intercourse (no birth control used) or have been sexually assaulted (raped). It may also be used when a barrier method of birth control has failed (for example, a condom breaks).

Exactly how emergency birth control pills prevent pregnancy is not clear. Some theories are that the hormones in the pills:

cause changes in the lining of the uterus that prevent implantation of a fertilized egg
prevent or delay ovulation (release of an egg from the ovary)
interfere with movement of the egg or sperm through the Fallopian tube to the uterus.

If the emergency birth control pills fail to prevent pregnancy, or you are already pregnant when you take them, there is no evidence that the pills will harm you or the baby. The pills will not end a pregnancy if a fertilized egg has already implanted in the uterus.

When is it used?

Your health care provider may prescribe emergency birth control pills if in the last 72 hours:

You had unprotected sexual intercourse, including sexual assaults.
A condom or diaphragm broke or tore during intercourse.

Some providers may provide a prescription for emergency birth control at the time of a routine exam so you have it if you need it.

How is it used?

There are different brands of emergency birth control pills. Some contain the hormones estrogen and progestin, and some contain just progestin. The dosage may vary depending on the type of pill prescribed. Usually you will take the first dose as soon as possible and not later than 72 hours after unprotected intercourse. You will take another dose 12 hours later. Carefully follow your health care provider's instructions for taking the pills prescribed for you.

The pills may cause nausea and vomiting. Your health care provider may prescribe another medicine to help prevent nausea and vomiting. You should take this pill an hour before taking the birth control pills. The antinausea pill may be included with the package of birth control pills.

What are the benefits of emergency birth control?

The benefits are prevention of:

unplanned pregnancies
abortions for unwanted pregnancies
the complications of pregnancies, delivery, abortion, or miscarriage.

If you take the pills within 72 hours of sexual intercourse, you greatly reduce the chance that you will become pregnant.

Who should not use emergency birth control?

You should not use emergency birth control if:

You know or suspect that you were already pregnant before you had unprotected sexual intercourse.
You are allergic to birth control pills.
You have abnormal vaginal bleeding.

If you have had blood clots from previous use of birth control pills, or if you have had certain other health problems, it may be safer to take pills that do not contain estrogen. Ask your health care provider if you should use the nonestrogen pill.

When should I call my health care provider?

You should call your health care provider within 24 hours after you have had unprotected sexual intercourse. The sooner you start taking the emergency birth control pills, the better your chances are of preventing pregnancy.

If you have taken emergency birth control pills, call your health care provider right away if:

You have pain, redness, or swelling in your leg.
Your arms, legs, hands, or feet are numb.
Vision problems, such as blurred vision or a partial or total loss of vision.

Also call your health care provider if your menstrual period does not start within 21 days of taking emergency birth control.

It is common to have breast tenderness after taking emergency birth control. The tenderness usually goes away in a few days and is not a medical problem.

Disclaimer: This content is reviewed periodically and is subject to change as new health information becomes available. The information provided is intended to be informative and educational and is not a replacement for professional medical evaluation, advice, diagnosis or treatment by a healthcare professional.

HIA File FMY4315F.HTM Release 9.0/2006