Emergency contraception

Emergency contraception is a method to prevent pregnancy in women who have had unprotected sex or when birth control methods have failed. It may be used after the following situations:

  • After a sexual assault or rape
  • When a condom breaks or a diaphragm slips out of place
  • When a woman forgets to take birth control pills
  • When you have sex and do not use any birth control


Emergency contraception medicine is not the same as the "abortion pill."

  • Emergency contraception is taken after unprotected sex to prevent pregnancy from occurring. It may also be called the "morning after" pill.
  • An abortion pill is for women who know they are pregnant and who want to end an early pregnancy. It is usually taken 4 to 7 weeks after becoming pregnant.

Emergency contraception prevents or delays the release of an egg from a woman's ovaries.

  • The method prevents pregnancy in the same way as regular birth control pills.
  • It is also possible that emergency contraceptives prevent a woman's egg from joining with a man's sperm (fertilization), and make it hard for the fertilized egg to implant correctly in the womb.


Several types of emergency contraception drugs are available. Two emergency contraceptive pills have been approved:

  • Plan B One-Step is a single tablet that contains 1.5 mg of levonorgestrel.
  • Next Choice is taken as two doses, which each contain 0.75 mg of levonorgestrel. Both pills can be taken at the same time or as two separate doses 12 hours apart.

Birth control pills, if available, may also be used for emergency contraception. It is best to talk to your health care provider about the correct dosage before doing this. In general, you must take two to five birth control pills at the same time to have the same effect as emergency contraception.

A copper-releasing intrauterine device (IUD) may be used as an alternative emergency contraception method. It must be inserted by your health care provider within 5 days of having unprotected sex. Your doctor can remove it after your next period, or you may choose to leave it in place to provide ongoing birth control.


Women ages 17 and older can buy Plan B One-Step and Next Choice at a pharmacy without a prescription or visit to the doctor. Younger girls need to contact a health care provider to get a prescription for these pills.

Emergency contraception works best when you use it within 24 hours of having sex. However, it may still prevent pregnancy for up to 5 days after you first had sex.

Emergency contraception may cause side effects. Most are mild. They may include:

  • Abdominal pain
  • Changes in menstrual bleeding
  • Fatigue
  • Headache
  • Nausea and vomiting

Stomach aches are most common when an estrogen-containing pill is used. Side effects are less common with Plan B, which contains a synthetic progesterone.

After you use emergency contraception, your next menstrual cycle may start earlier or later than usual. Your menstrual flow may be lighter or heavier than usual.

  • Most women get their next period within 7 days of the expected date.
  • If you do not get your period within 3 weeks after taking emergency contraception, you might be pregnant. Contact your health care provider.

Sometime, emergency contraception does not work. However, research suggests that emergency contraceptives have no long-term effects on the pregnancy or developing baby.


You should not use emergency contraception if:

  • You think you have been pregnant for several days
  • You have vaginal bleeding for an unknown reason (talk to your doctor first)

You may be able to use emergency contraception even if you cannot regularly take birth control pills. Talk to your doctor about your options.

Emergency contraception 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.

Alternative Names

Morning-after pill; Postcoital contraception; Birth control - emergency; Plan B


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Amy JJ, Tripathi V. Contraception for women: an evidence based overview. BMJ. 2009;339:b2895.doi:10.1136/bmj.b2895.

Prine L. Emergency contraception: myths and facts. Obstet Gynecol Clin N Am. 2007;34:127–136

Mischell DR. Family planning: contraception, sterilization, and pregnancy termination. In: Katz VL, Lentz GM, Lobo RA, Gershenson DM, eds. Comprehensive Gynecology. 5th ed. Philadelphia, Pa: Mosby Elsevier; 2007:chap 14.

Update Date: 2/28/2012

Reviewed by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; Susan Storck, MD, FACOG, Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Bellevue, Washington; Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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