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Emergency contraception

Emergency contraception

Emergency contraception can help keep you from getting pregnant if you had sex without using birth control or if your birth control method did not work. There are two types of FDA-approved emergency contraceptive pills (ECPs). Some ECPs can work when taken within five days of unprotected sex or when your birth control does not work correctly. Some ECPs are available without a prescription.

What is emergency contraception?

Emergency contraception is a method of birth control you can use if you had sex without using birth control or if your birth control method did not work correctly. You must use emergency contraception as soon as possible after unprotected sex.

Emergency contraception pills are different from the abortion pill. If you are already pregnant, emergency contraception pills do not stop or harm your pregnancy.

Emergency contraception has also been called the "morning-after pill," but you do not need to wait until the morning after unprotected sex to take it.

Emergency contraception is not meant to be used for regular birth control. Talk to your doctor or nurse about regular birth control to help prevent pregnancy. Nearly half of all pregnancies in the United States are unplanned.1

What types of emergency contraception pills are available?

In the United States, there are two types of FDA-approved ECPs available for emergency contraception:2,3

  • ella® (ulipristal acetate)
  • Plan B One-Step® (LNG-only) — Plan B One-Step® has several generic versions. Some common generic versions include AfterPill™, My Way®, Next Choice One Dose™, and Take Action™.

How do emergency contraception pills prevent pregnancy?

Research shows that emergency contraception pills work mostly by preventing or delaying ovulation (the release of an egg from the ovary). Less commonly, emergency contraception may prevent fertilization of the egg by the sperm if ovulation has already happened.4,5 If a fertilized egg has already implanted in your uterus (you are pregnant), emergency contraception pills will not stop or harm your pregnancy.6

When should I think about using emergency contraception?

Consider using emergency contraception if you had sex and:

  • You didn't use birth control
  • You think your birth control didn't work (see the list in the next section)

Consider asking your doctor for a prescription for emergency contraception pills, or having some type of emergency contraception pill already at home or with you in case you need it.

What does it mean for birth control to "fail" or not work correctly?

Depending on the method of birth control you use, not working correctly means different things.

Birth control method

Failure rate
(number of pregnancies per 100 women in a year)

Examples of what can go wrong with your birth control

Natural planning method

24 out of 100 women get pregnant

You have sex on the fertile days of your cycle and do not use another form of birth control (such as a condom or spermicide)

Cervical cap

23 out of 100 women get pregnant
(women who have given birth)

13 out of 100 women get pregnant
(women who have never given birth)8

Slips off the cervix or has a tear/hole in the cap; is not used with spermicide

Male condom

18 out of 100 women get pregnant

Breaks or comes off at any time during sex

Diaphragm with spermicide

12 out of 100 women get pregnant

Slips out of place or has a tear or hole in it; is not used with a spermicide

Hormonal birth control pills

9 out of 100 women get pregnant

You do not take a pill every day, as directed

Vaginal ring

9 out of 100 women get pregnant

You put it in too late or take it out too soon during the month

Birth control patch

9 out of 100 women get pregnant

You put it on too late or take it off too soon during the month, or it does not stick to your skin correctly

Hormonal birth control shot

6 out of 100 women get pregnant

You are more than two weeks late getting the shot

Intrauterine device (IUD)

Less than 1 out of 100 women get pregnant*

Comes out before you are ready for it to be removed

Implantable rod

Less than 1 out of 100 women get pregnant

The rod is not removed or replaced in time (up to three years after it is placed in your arm)

*This number may be higher, depending on when the IUD came out and how long before it was noticed.

How do I get emergency contraception?

It depends on the type of emergency contraception you need.

  • Plan B One-Step® and similar generic versions are available in stores without a prescription to anyone, of any age. If you do not see it on the shelf, ask the pharmacist for help.
  • Levonorgestrel tablets (two-pill generic Next Choice® and LNG tablets 0.75 mg) are available to people aged 17 and older without a prescription. These brands are sold from behind the pharmacy counter.
  • ella® is available only by prescription from your doctor, nurse, or family planning clinic.

To find a low-cost family planning clinic for emergency contraception, enter your ZIP code into the clinic finder on this page.

How quickly should I use emergency contraception after unprotected sex?

Emergency contraception works best when you use it as soon as possible after unprotected sex. If you are unable to take it right away, emergency contraception can still work to prevent pregnancy if taken up to three to five days after unprotected sex. How long after depends on which type of emergency contraception you use.

  • Take Plan B One-Step® or a generic version as soon as possible within three days (or 72 hours) after unprotected sex.
  • For the two-dose version (Next Choice®, LNG tablets 0.75 mg), take one pill as soon as possible within 3 days and the second pill 12 hours later.
  • Take ella® (ulipristal acetate) as soon as possible within five days (or 120 hours) after unprotected sex.

Does emergency contraception have side effects?

Yes, but the side effects are rarely serious. Side effects differ for each woman and may include:

  • Headache
  • Abdominal pain
  • Tiredness (fatigue)
  • Dizziness
  • Nausea
  • Breast pain

The side effects are usually mild and do not last long. Your next period may come early or late, and you may have spotting (light bleeding that happens between menstrual periods).

Does body weight affect how well emergency contraception works for women?

Maybe. Research from the Centers for Disease Control and Prevention shows that ECPs may not prevent pregnancy as often for obese women (with a body mass index, or BMI, of 30 or greater) as for women who are not obese.9

Find out your BMI. If your BMI is greater than 30, talk to your doctor or nurse about your risk and your options for emergency contraception.

How can I get free or low-cost emergency contraception?

Under the Affordable Care Act (the health care law), most insurance plans cover FDA-approved prescriptions for emergency contraception and birth control at no cost to you. This includes Plan B One-Step® and ella®. Since you can buy Plan B One-Step® or the generic version in a store, without a prescription, call your insurance company to find out if your plan covers over-the-counter emergency contraception. You may need to get a prescription from your doctor if you want your insurance plan to pay for it.

  • If you have insurance, check with your insurance provider to find out what's included in your plan.
  • If you have Medicaid, your insurance may cover emergency contraception. Coverage varies between states, so check with your state's Medicaid program to learn about your benefits.
  • If you don't have insurance, find a family planning clinic in your area. They may provide emergency contraception for free or at low cost.
  • To see if you are eligible for low-cost or no-cost health insurance, visit

For information about other services covered by the Affordable Care Act, visit

Can I get emergency contraception pills before I need them?

Yes. Your doctor can give you a prescription to fill so you can have emergency contraception at home to use when you need it. Or, you can buy some types of emergency contraception pills from a store at any time.

Can I use emergency contraception as my regular form of birth control?

No. Do not use Plan B One-Step® (or a generic version) or ella® as your regular birth control. Most other types of FDA-approved birth control, when used correctly, are much better at preventing pregnancy than emergency contraception pills and usually cost less. Also, while emergency contraception pills are safe for emergency use, they have not been tested as regular birth control and are not approved by the FDA for this purpose.

Women who are sexually active will need to use birth control to prevent pregnancy. What type of regular birth control you can use right away depends on the type of emergency contraception you take.

  • If you take ella®, do not use hormonal birth control (the pill, patch, vaginal ring, or intrauterine device) for at least five days after you take ella. Using them together may cause ella® not to work. Instead, use a condom, diaphragm, sponge, or cervical cap until you get your next period.10
  • If you take Plan B One-Step® (or a generic version), you can start right away or continue using a regular form of birth control.

Read more about different types of birth control in our birth control methods fact sheet.

Will emergency contraception pills affect my next period?

Maybe. After you take an emergency contraception pill, your next period may come sooner or later than normal. Most women will get their period within a week of the expected date. Your period also may be heavier, lighter, spotty, and more or less painful than is normal for you.

If you do not get your period more than one week after expected or if you think you might be pregnant after taking emergency contraception pills, take a pregnancy test to find out for sure.

Will emergency contraception protect me from sexually transmitted infections (STIs)?

No. Emergency contraception does not protect you from STIs (PDF, 187 KB). To lower your risk of getting an STI, always use condoms when you have vaginal, oral, or anal sex.

See a doctor right away if you think you may have been exposed to an STI.  Also, you can get medicine to help prevent HIV, the virus that causes AIDS.

If you were sexually assaulted, go to the nearest hospital emergency room as soon as possible. The National Sexual Assault Hotline at 800-656-HOPE (4673) can help you find a hospital able to collect evidence of sexual assault. You can get medicine to prevent HIV and other STIs and get emergency contraception to prevent pregnancy.

Did we answer your question about emergency contraception?

For more information about emergency contraception, call the OWH Helpline at 1-800-994-9662 or contact the following organizations:


  1. Finer, L.B., Zolna, M.R. (2016). Declines in unintended pregnancy in the United States, 2008-2011.The New England Journal of Medicine; 374(9):843–52.
  2. Food and Drug Administration. (2013). FDA approves ella®™ tablets for prescription emergency contraception.
  3. Food and Drug Administration. (2013). FDA approves Plan B One-Step® emergency contraceptive for use without a prescription for all women of child-bearing potential.
  4. Gemzell-Danielsson K., Berger, C., Lalitkumar, P.G. (2014). Mechanisms of action of oral emergency contraception. Gynecological Endocrinology 30 (10): 685-687.
  5. Gemzell-Danielsson K., Berger C., Lalitkumar, P. G. (2013). Emergency contraception — mechanisms of action.Contraception; 87(3): 300–308.
  6. Food and Drug Administration. (2015). FDA’s decision regarding Plan B: Question and answers.
  7. Centers for Disease Control and Prevention. (2014). Effectiveness of Family Planning Methods.
  8. Food and Drug Administration. (2016). Birth Control: Medicines to Help You.
  9. Curtis, K.M., Tepper, N.K., Jatlaoui, T.C., et al. (2016). U.S. Medical Eligibility Criteria for Contraceptive Use, 2016. MMWR Recomm Rep; 65(RR-3):1–104. Appendix A.
  10. Food and Drug Administration. (2015). ella® (PDF, 398 KB).