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Birth Control

Emergency Contraception

“The condom broke.”

“I didn’t think we were going to have sex.”

“I forgot to take my pill.”

“I was raped.”

In an ideal world, we would always plan ahead, but the reality is that many of us have found ourselves at risk of a pregnancy that is unwanted. Fortunately, if this happens, we are no longer limited to waiting and worrying. 

Emergency contraception (EC) is contraception that can be used after unprotected intercourse or a birth control failure to prevent pregnancy. EC can be used any time from immediately after unprotected intercourse to up to five days after. Using emergency contraception greatly decreases the chances of a pregnancy. Emergency contraception does not work if you are already pregnant. It does not cause abortion.

There are now four safe and effective methods of emergency contraception available: commercial forms of emergency contraception pills (ECPs), combined birth control pills, progestin-only pills, and IUDs.

In the United States, Plan B, Plan B One-Step, and Next Choice are available without prescription to women and men seventeen years and older. Women age sixteen and under need a prescription. However, in some states, pharmacists are allowed to prescribe ECPs directly to women of any age, eliminating the need for a clinic visit. As of 2011, the following states allow this: Alaska, California, Hawaii, Maine, Massachusetts, New Hampshire, New Mexico, Vermont, and Washington state. The newest commercial ECP, Ella, is available only by prescription regardless of age.

Although some forms of emergency contraception have been used for several decades, most women and many providers still do not know that it is available and effective. If more women knew about and were able to get emergency contraception when needed, many unintended pregnancies and abortions could be prevented.

Emergency Contraceptive Pills (ECPs)

Emergency contraceptive pills (ECPs), also known as “postcoital contraception” or the “morning-after pill,” work by changing a woman’s hormone levels in the same ways birth control pills and other hormonal methods work. They give the body a short, high burst of synthetic hormones that disrupt natural hormone production needed for ovulation and pregnancy. ECPs prevent pregnancy by inhibiting ovulation or by disrupting egg and sperm transport, fertilization, or implantation. Most women can safely use ECPs even if they cannot use birth control pills as their regular method of birth control. ECPs can be used within five days of unprotected sexual intercourse.

It is not advisable to use ECPs as your only protection against pregnancy if you are sexually active or planning to be, because they are not as effective as other contraceptive methods. Using ECPs frequently won’t hurt you, but it will get expensive.

The FDA currently approves three types of emergency contraceptive pills: pills that contain only progestin, pills that contain both progestin and estrogen, and pills that contain the antiprogestin ulipristal acetate. (Mifepristone, or RU‑486, can also be used for emergency contraception. It has a lower pregnancy rate and fewer side effects than currently available pills 25 but has not been approved for this use in the United States and is very expensive, $350– $650.)

Progestin-only ECPs include Plan B, Plan B One-Step, Next Choice, and the minipill. Progestin-only ECPs are slightly more effective than combination pills and cause few if any side effects.

The second type of ECP uses both estrogen and progestin. Currently, no combination pills are sold specifically as ECPs, but many brands of the daily birth control pill can be used at a higher dose for emergency contraception. To find out which pills you can use and the proper dose for each, call the Emergency Contraception Hotline at 1-800-584-9911 or go to ec.princeton.edu/questions/dose.html. This method often causes nausea and discomfort, but many women believe that the protection is worth it.

The newest ECP, the antiprogestin pill Ella, is more effective than progestin-only pills at preventing pregnancy, but it is more expensive.

Health Concerns

Because ECPs are used for only a short time, most women—including some who have been told by a doctor that they shouldn’t take birth control pills—can safely take them. If you have a serious health problem that prevents you from taking regular birth control pills, consult a health-care provider. Certain medications may interfere with Ella, so discuss any other medications you’re taking with your provider.

If you could be pregnant already, it is a good idea to take a pregnancy test before using emergency contraception. ECPs should not be used by women who are already pregnant—not because the pills are thought to be harmful, but because they are ineffective at terminating established pregnancies. If after taking the pills you become pregnant anyway, there is no evidence of danger to the fetus.

How to Use

Some people call emergency contraceptive pills “morning-after pills.” But you do not have to wait until the morning after. You can start the pills right away or up to five days after you have had unprotected intercourse—that is, intercourse during which you did not use birth control or your birth control may have failed. The sooner progestin-only or progestin-plus-estrogen ECPs are started within the five-day (120-hour) window, the more effective they are. Ella, however, is equally effective on all five days after unprotected sex.


Plan B and Next Choice reduce the chance of pregnancy by 88 to 95 percent. If a hundred women have unprotected intercourse, about eight will become pregnant; if the one hundred women use Plan B, only one will become pregnant. Plan B is 89 percent effective for all women who take the pills within the first three days. Taking the pill within the first twenty-four hours may increase effectiveness to as much as 95 percent.

Combined estrogen and progestin pills are slightly less effective than progestin-only pills. They reduce the chance of pregnancy by 75 percent.

Ella reduces the risk of pregnancy by 98 percent. It is equally effective regardless of which day it is taken.

Side Effects

Progestin-only pills have few or no side effects. Nausea and vomiting are the most common negative effects of taking emergency contraception pills that contain both estrogen and progestin; about half the women who take them feel nauseated, and about 20 percent vomit. For this reason, some practitioners advise taking the pills with food or with an antinausea medication such as an over-the-counter remedy for motion sickness. Other negative effects include breast tenderness, dizziness, abdominal pain, and headaches. Using combination pills for emergency contraception may also change the timing of your next menstrual period: It may begin a few days earlier or a few days later than usual.

The most common side effects of Ella are abdominal pain, cramping, and irregular bleeding. Less common side effects include headache and nausea.

How to Use the IUD as EC

The ParaGard IUD, also known as the Copper T, is very effective at preventing pregnancy if inserted within five days after unprotected intercourse. The IUD works as an emergency contraceptive by rendering sperm unable to swim, changing the unfertilized egg, or preventing the implantation of a fertilized egg. Once inserted into the uterus, ParaGard can be left in place and used as your regular method of birth control for up to twelve years.

Women who cannot use the IUD for birth control (see p. 240) should not use it for emergency contraception, either.


Using the ParaGard IUD within five days of unprotected intercourse is more than 99.9 percent effective at preventing pregnancy. 

Where to Get Emergency Contraception

Emergency contraception is available at familyplanning clinics, health-care providers’ offices, and pharmacies. You can ask your provider to write you a prescription in advance so you have it on hand if you need it. The IUD must be inserted by a trained provider.

Frequently Asked Questions

  • What is my risk of pregnancy from unprotected intercourse? The likelihood of becoming pregnant after a single act of unprotected intercourse depends on where you are in your menstrual cycle and on your body’s unique fertility levels.
  • What if I engage in unprotected intercourse but ejaculation does not occur? Is sperm present in pre-ejaculatory fluid? The chance of pregnancy is probably extremely low. Three small studies found no motile sperm in pre-ejaculatory fluid.26 (However, HIV can be detected in pre-ejaculatory fluid.) If you are worried about the possibility of pregnancy, or if you are not sure whether ejaculation did occur, consider using emergency contraception.

  • When should my next period come after I take emergency contraceptive pills? After taking ECPs, some women have a period early, and some women have irregular bleed‑ing that is not really a period. The duration of the irregular bleeding is not predictable. You should have another normal period within the next month. If not, you should get a pregnancy test to make sure you’re not pregnant.

  • What if I have sex after taking emergency contraceptive pills? Emergency contraceptive pills do not act as ongoing birth control. They will not protect against pregnancy from unprotected intercourse that occurs after the pills are taken.

  • Is there a limit to the number of times emergency contraceptive pills can be used? There are no safety concerns with using ECPs repeatedly. However, ECPs are not as effective as many other methods of contraception. EC is also expensive to use repeatedly. You (and your wallet) might benefit from finding an ongoing method of contraception.

For free information about preventing pregnancy after unprotected intercourse and to obtain names and telephone numbers of health care professionals in your area who can provide emergency contraception, call the Emergency Contraception Hotline at 1-800-584-9911 or visit not-2-late.com

Abortion rights opponents oppose EC and claim it is abortion, which ends a pregnancy, rather than contraception, which prevents one. However, EC works either by preventing ovulation or by preventing implantation of a fertilized egg in the uterus. The international medical community agrees that pregnancy begins with implantation, so EC acts before pregnancy even occurs.

Excerpted from the 2011 edition of Our Bodies, Ourselves. © 2011, Boston Women's Health Book Collective.


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