Birth control - emergency

Alternative names
Morning-after pill; Postcoital contraception; Emergency contraception

Emergency contraception is a method of birth control that can be used within three days of sexual intercourse.


Emergency contraception is a “second chance” method of birth control for women who have had unprotected sexual intercourse or who have had a birth control failure, such as a condom breaking. Unlike most types of birth control, which must be in place prior to intercourse emergency contraception can be used up to 3 days after intercourse.

Several types of emergency contraception drugs are available. Most contain hormonal medications that are related to the female hormones estrogen or progesterone. These hormones are similar to the medications in birth control pills, but when used for emergency contraception, they are taken in higher doses. Usually, emergency contraception drugs are taken in 2 doses, given 12 hours apart.

Two drugs are specifically FDA-approved for emergency contraception: Plan B (containing levonorgestrel, a progesterone-like medication) and Preven (containing levonorgestrel and ethinyl estradiol, a medication related to estrogen).

Regular types of birth control pills can also be used for emergency contraception. You must take 2 - 5 “regular” pills together to equal a single dose of emergency contraception.

Another type of emergency contraception, the intrauterine device (IUD), does not involve any medications. An IUD is a birth control device that is inserted into a woman’s uterus by a physician. If the IUD is inserted within 5 days after unprotected intercourse, it also acts as emergency contraception. IUDs are intended to provide long-term birth control for 1-10 years.

Emergency contraception has several potential effects on a woman’s reproductive system that could help to decrease her risk of getting pregnant. Emergency contraceptive drugs appear to work primarily by preventing or delaying egg release (ovulation) from the ovaries. They may also slow egg or sperm transport in the fallopian tubes, and they may make the uterine lining less hospitable for implantation of a pregnancy. For example, IUDs are toxic to sperm and change the uterine lining so that implantation is less likely.

Emergency contraception can be used following many different situations of unprotected intercourse including rape, unplanned acts of intercourse, or when a birth control method fails. For instance, emergency contraception can help to prevent pregnancy after a condom breaks, a diaphragm slips out of place, or birth control pills are forgotten.

Emergency contraception is available by prescription only. An IUD requires an office visit, but a telephone call to the health care provider’s office is usually all a woman needs to do in order to start emergency contraception medication.

Some health care providers will provide their patients with a prescription for an emergency contraception drug to keep at home, in case it is needed in the future.

A toll-free hotline (1-888-NOT-2-LATE) is available to get more information about emergency contraception. Operators at this number may also be able to provide contact information for physicians in local areas who prescribe emergency contraception.

The first dose of emergency contraception medications can be taken up to 72 hours after unprotected intercourse. The second dose is taken 12 hours after the first. These drugs are most effective when taken as soon as possible after intercourse.

Oral emergency contraception medications prevent about 75-89% of pregnancies that occur after unprotected sexual intercourse, and they work best if taken as soon as possible after intercourse. Emergency contraception by IUD insertion is even more effective.

Not every woman who has unprotected intercourse will get pregnant. The risk of pregnancy depends on many factors, especially the time in the menstrual cycle that intercourse occurs. For instance, if 100 women have unprotected intercourse once in the middle 2 weeks of their menstrual cycles, about 8 will become pregnant. If they all use emergency contraception within 72 hours of intercourse, only 1 to 2 will become pregnant.

Mild and often unpleasant side effects from emergency contraception medications are common, such as nausea, vomiting, abdominal pain, fatigue, headache, and changes in menstrual bleeding. Nausea and vomiting are the most troublesome side effects - nausea occurs about 50% of the time and vomiting about 20% of the time after emergency contraceptive pills are taken.

Some doctors recommend taking an anti-emetic medication (a drug to prevent nausea and vomiting) before taking the emergency contraception pills to prevent these side effects. Progesterone-only emergency contraceptives cause less nausea and vomiting than methods that contain both progesterone and estrogen-like medications.

After taking emergency contraception, a woman’s next menstrual cycle may start earlier or later than expected and the menstrual flow may be lighter or heavier than usual. Still, most women will start their next period within 7 days of the expected date. If a woman’s menstrual bleeding does not start within 3 weeks after taking emergency contraception, she might be pregnant and should call or visit her health care provider.

Emergency contraception drugs do not appear to harm an early pregnancy. However, women who believe that they are already pregnant and may have been for longer than several days should not take such drugs, since their effects have not been well studied. Also, women who have vaginal bleeding for an unknown reason should discuss this with their health care provider before taking emergency contraception.

Women who cannot take birth control pills regularly in most cases may still be able to use emergency contraceptives, but they should also discuss this option with their health care provider.

IUD placement has risks of pelvic infection and uterine injury, although these are quite rare. Long-term use of an IUD for birth control may cause side effects such as heavy menstrual bleeding and painful menstrual cramps.

Women who are interested in IUD placement for emergency contraception should discuss the risks and benefits of IUD use with their health care providers.

Some people have confused emergency contraception drugs with the “abortion pill,” but they are not the same thing. A woman who knows she is pregnant takes the “abortion pill” with the intent to terminate the early pregnancy (usually 4 to 7 weeks after conception). Emergency contraception pills are taken after unprotected sex to prevent conception from occurring.

However, if emergency contraception is taken after the sperm and egg have already joined (but before the fertilized egg has implanted in the uterine wall), pregnancy may still be prevented by inhibition of transport through the tubes or implantation in the uterus. So, sometimes emergency contraception prevents fertilization, and sometimes it prevents implantation after fertilization has already occurred. However, emergency contraception will not end an early pregnancy that has already implanted in the uterus.

If emergency contraception fails and the woman becomes pregnant, there do not appear to be any long-term effects on the pregnancy or the fetus.

Emergency contraception provides a second chance at preventing undesired pregnancies, but it should not be used as a routine birth control method, because it is actually less effective at preventing pregnancies than most types of birth control. Unprotected intercourse also puts a woman at risk of sexually transmitted infections such as HIV, and emergency contraception does not protect against infections. Health care providers can provide counseling and possibly treatment if this is a concern.

There is a “morning-after” medication combination for women or men who have been raped or who believe they may have been exposed to HIV infection through unprotected sex or needle-sharing - but this is a much more involved course of drugs that can have serious side effects and may not always prevent infection. If you think you have been exposed to HIV, contact an emergency room or knowledgeable HIV specialist or organization and ask about “postexposure prophylaxis” immediately.

Johns Hopkins patient information

Last revised: December 2, 2012
by Arthur A. Poghosian, M.D.

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