Center for Young Women's Health

Emergency Contraception



  • EC can be used within 3-5 days of sexual intercourse, depending on the type of pill.
  • Taking EC lessens the chance of pregnancy, but is not 100% effective.
  • Talk with your health care provider about the best regular form of birth control for you.

What is emergency contraception?

Emergency contraception (EC) is a backup method of birth control for preventing pregnancy after unprotected sex. Even though it is commonly called the "morning-after pill' it can actually be used within 5 days (120 hours) of unprotected intercourse. EC works better the sooner you take it.

When should a women use emergency contraception?

Emergency contraception (EC) should be used if:

How does emergency contraception work?

The medications work by giving a strong short burst of hormones that changes the cycle and prevents ovulation.


It's important to remember that EC doesn't continue to protect against pregnancy during the rest of the menstrual cycle. You should use a barrier method, such as a condom until your next period.


Does emergency contraception (EC) cause an abortion?

Emergency contraception (EC) does not work if a woman is already pregnant. EC will NOT cause an abortion.


How is emergency contraception taken?

There are three types of emergency contraception that use hormone pills:

  1. The first "morning-after" emergency contraception pill methods approved in the United States are: Plan B One-Step™ and Next Choice®. Both products contain only one kind of hormone, a progestin, and it comes as 1 or 2 pills. A woman can take the total dose of 1.5 mg levonorgestrel in Plan B One-Step™ as one pill, or use Next Choice® and take both pills (.75 mg in each tablet) at the same time or take one pill followed by the second pill twelve hours later. Both kinds of EC work best if taken within 3 days (72 hours) of unprotected sex, but can be taken up to 5 days but the earlier it is taken the more effective it is. No prescription is needed for girls 15 and older.
  2. Ella™ (urlipristal acetate or UPA) is an emergency contraceptive that works by stopping or delaying ovulation. It's one pill (one dose) that can be taken up to 5 days or 120 hours after unprotected intercourse. A prescription is needed.
  3. Another type of emergency contraception uses regular birth control pills, which contain two hormones, estrogen and progestin. There are 2 doses. The first dose may be 2, 4, or 5 pills depending on the brand of birth control pills used, and is taken within 120 hours (5 days) of unprotected sex. The second dose is taken 12 hours after the first dose. A health care provider must prescribe how many pills should be taken for this kind of emergency contraception. This method is less effective than the other two, and is more likely to cause nausea.

How effective is emergency contraception?

It's important to remember that emergency contraception doesn't always work. It doesn't guarantee that pregnancy will be prevented. Emergency contraception lowers your risk of pregnancy by 89%. The risk of getting pregnant depends on when in your menstrual cycle you had sex and what kind of birth control you use. You're more likely to get pregnant around the time when the ovary releases an egg (ovulation).


On August 13, 2010, the U.S. Food and Drug Administration (FDA) approved a new emergency contraception pill, Ulipristal Acetate (Ella™). It became available to women in the United States on Dec. 1, 2010, however, it's been used in parts of Europe since 2009. You'll need a prescription to buy it in the United States.


The biggest differences between Ella also called UPA (short for Ulipristal Acetate) and other emergency contraception methods are:

The best way to prevent pregnancy is to use a regular birth control method such as condoms or birth control pills, or to not have sexual intercourse.

Is emergency contraception (EC) safe?

Yes. Millions of women have used emergency contraception (EC) without any problems.


Does emergency contraception (EC) cause birth defects?

Emergency contraception does not cause birth defects or affect the health of future children that a woman may have.


Does emergency contraception (EC) have any side effects?

EC is tolerated well and side effects are usually absent or mild. A few percent of women may have nausea, dizziness; headache and/or stomach pain, temporary irregular menstrual periods, and breast tenderness with Plan B One Step™, Next Choice® or Ella™. Some women may complain of moderate nausea and vomiting if regular birth control pills are used (for EC). Side effects from emergency contraception (when using regular birth control pills) most often go away after 1-2 days. There are over-the-counter medicines you can get such as (Dramamine II or Bonine) for nausea.


Where can I get emergency contraception?

In the United States women 15 and older can get (progestin-only) EC at pharmacies without a prescription. For teens under the age of 15, EC requires a prescription. You may need to check many different pharmacies, because EC is not available in all pharmacies.


Use the EC website to find a doctor or pharmacy if you have any questions about emergency contraception.


Be ready to answer the following questions:

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

Emergency contraception is not meant to be a regular method of birth control. It's meant to be a one-time emergency treatment. Emergency contraception can be used when a condom breaks, when a diaphragm or cervical cap gets moved, if a woman is raped, or any time when there is unprotected sex. You should not use emergency contraception as your only protection against pregnancy, because this method doesn't work as well as other types of birth control. Also, emergency contraception does not protect against STDs.


When can I expect my next menstrual period after I have taken emergency contraception?

Your period should start within 2-4 weeks after taking EC. Your next period may start a little early or a few days later than usual. You may also have spotting, however; this is neither common nor serious. If your next period is late, contact your health care provider and get a pregnancy test.


What if I have problems after I have taken emergency contraception (EC)?

If you have any problems after you take emergency contraception, you can contact your health care provider.


You should definitely call your health care provider if:

Do I need to do anything else to prevent pregnancy after I have taken emergency contraception?

Yes. You should talk to your health care provider about using a regular type of birth control method. Until you have your next menstrual period, it is best not to have sexual intercourse. If you decide to have intercourse, make sure to use a barrier method, such as a condom, every time you have sex even if you are taking birth control pills. Your health care provider may suggest that you start birth control pills right away after emergency contraception. Find out more about birth control methods so you can start thinking about what method will be best for you.

We hope that you have learned a lot about emergency contraception (EC) and that we have answered your questions. Below are the key points to remember about EC so you can be a resource to your family, friends, and others.

Key Points to Remember about Emergency Contraception (EC):

Be sure to talk with your health care provider about how you can prevent pregnancy and stay healthy.


On April 30, 2013, the Federal Drug Administration (FDA) approved the following: Girls who are 15 and older can buy Plan B One-Step™ emergency contraception without a prescription. According to the pharmaceutical company that makes Plan B One-Step™, a prescription will still be required for a few months or until the product (with new packaging instructions) is in stores.


Written and reviewed by the CYWH Staff at Boston Children's Hospital


Updated: 5/23/2013


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