FAQ114, May 2019

PDF Format

Emergency Contraception

What is emergency contraception?

Emergency contraception (EC) reduces the chance of pregnancy after unprotected sexual intercourse. Common situations in which EC could be used include forgetting to take several birth control pills in a row, having a condom break or slip off, or not using a birth control method during sex. It also can be used after a woman has been raped.

How does emergency contraception work?

Using EC does not cause an abortion. An abortion ends an existing pregnancy. EC prevents pregnancy from occurring. EC must be used soon after unprotected sexual intercourse to be effective. It does not work if pregnancy has already occurred.

What are the different types of emergency contraception?

There are two types of EC: 1) the copper intrauterine device (IUD) and 2) EC pills. There are three types of EC pills: 1) ulipristal, 2) progestin-only pills, and 3) combined EC pills. Some EC pills can be bought over the counter without a prescription. Others require a prescription. An obstetrician–gynecologist (ob-gyn) or other health care professional must insert the IUD.

What is the most effective form of emergency contraception?

The copper IUD is the most effective form of EC. When taken as directed, ulipristal is the most effective type of EC pill, followed by the progestin-only pill. Combined EC pills are not as effective in preventing pregnancy as the progestin-only EC pill.

How does the copper intrauterine device work?

The copper IUD works mainly by making sperm less able to fertilize the egg. It is the most effective EC method in preventing pregnancy. When used for EC, the copper IUD should be inserted within 5 days of having unprotected sex. You then can rely on the copper IUD for long-term birth control (for up to 10 years). You can have the IUD removed at any time if you wish to become pregnant.

A health care professional must insert the IUD. You can call your ob-gyn or other health care professional or go to a family planning clinic to have the IUD inserted.

What are the possible side effects of using the copper intrauterine device?

With the copper IUD, menstrual pain and bleeding may increase in the first few months of use. Pain can be relieved with over-the-counter pain relievers. Heavy bleeding sometimes can be treated with a medication. Both side effects usually decrease within 1 year of using the copper IUD.

How do emergency contraception pills work?

  • Ulipristal—This medication affects how progesterone works in the body. It is thought to delay or prevent ovulation. It can be taken up to 5 days after unprotected sex with no decrease in effectiveness. When taken as directed, ulipristal is more effective in preventing pregnancy than progestin-only or combined EC pills. Ulipristal is available by prescription only.
  • Progestin-only EC—This is a single pill that should be taken as soon as possible after having unprotected sex. Progestin is a hormone in birth control pills and other forms of hormonal birth control. It stops or delays ovulation to prevent pregnancy. It is most effective when taken within 3 days of unprotected sex. It is moderately effective when taken within 5 days. This pill is available without a prescription to anyone of any age. It can be found on store shelves, usually in the family planning section.
  • Combined birth control pills—Birth control pills that contain both estrogen and progestin are called combined hormonal birth control pills. Taken in higher-than-usual amounts, they can be used for EC. You need to take combined EC pills as soon as possible up to 5 days after having unprotected sex. They work by delaying ovulation. They are taken in two doses. The number of pills needed for EC differs for each brand of pill. An ob-gyn, other health care professional, or pharmacist can tell you how many pills you should take for the type that you have. You also can find this information at the website

How often can I use emergency contraception pills?

EC pills can be used more than once during a single menstrual cycle, but you should not rely on EC pills as a long-term birth control method. EC pills are not as effective in preventing pregnancy as using a birth control method consistently and correctly. There also may be more side effects from frequent use of EC than from use of a standard birth control method. If you are not using birth control, talk with your ob-gyn or other health care professional about which method would work best for you.

What are the possible side effects of taking emergency contraception pills?

EC pills have not been shown to cause any serious complications. Your next period may not occur at the expected time. You may have irregular bleeding or spotting in the week or month after taking EC pills that goes away on its own. Other short-term side effects of EC pills can include the following:

  • Headache
  • Nausea and vomiting (especially if you are taking combined EC pills)
  • Breast tenderness
  • Abdominal pain
  • Dizziness
  • Fatigue

Is there anything that decreases the effectiveness of emergency contraception pills?

Being overweight or obese may decrease the effectiveness of EC pills. If you are overweight or obese, you may want to consider having a copper IUD inserted. Copper IUDs are effective in women of any weight.

How can I get emergency contraception as soon as possible?

The progestin-only pill is available over the counter in pharmacies and other stores to anyone of any age. The progestin-only pill usually can be found in the family planning section. Not all stores carry the over-the-counter EC pill, so it is best to call ahead to see if it is available.

You can get EC pills ahead of time so that you always have them if needed. You can purchase them in advance at a pharmacy or online. Many pharmacies offer online ordering and shipping services.

Ulipristal, combined birth control pills, and the copper IUD are available only by prescription. To get a prescription or to have the copper IUD inserted, call your ob-gyn or other health care professional or go to a family planning clinic. Another option is to go to You also can ask your ob-gyn or other health care professional to give you a prescription for these EC methods at any routine health care visit. That way, you are always prepared if you need to use these forms of EC.

How do I start or go back to using a birth control method after taking emergency contraception pills?

How you start or go back to using birth control after using EC pills depends on which type of EC pills you used:

  • If you used the progestin-only pill or combined EC pills, you can resume or start any birth control method right away. For the next 7 days, you also must use a barrier method (condoms, diaphragm, and spermicides) along with your regular birth control method or not have sexual intercourse.
  • If you used ulipristal and want to resume or start using a hormonal birth control method (pill, patch, ring, implant, shot, or hormonal IUD), you need to wait to do so until 5 days after taking ulipristal. You also must use a barrier method (or not have sexual intercourse) until your next menstrual period. Using a hormonal birth control method and taking ulipristal at the same time can reduce the effectiveness of both medications.

Do I need follow-up care after using emergency contraception?

No tests or procedures are needed after taking EC. You should have a pregnancy test if you have not had a period within a week of when you expect it. None of the EC pills have been shown to harm a pregnancy or the health of the fetus if you already are pregnant.

Keep in mind that EC does not prevent sexually transmitted infections (STIs). If you are at risk of getting an STI and have had unprotected sex, see your ob-gyn or other health care professional.


Egg: The female reproductive cell made in and released from the ovaries. Also called the ovum.

Emergency Contraception (EC): Methods that are used to prevent pregnancy after a woman has had sex without birth control, after the method has failed, or after a rape.

Estrogen: A female hormone produced in the ovaries.

Fetus: The stage of human development beyond 8 completed weeks after fertilization.

Hormone: A substance made in the body that controls the function of cells or organs.

Intrauterine Device (IUD): A small device that is inserted and left inside the uterus to prevent pregnancy.

Menstrual Cycle: The monthly process of changes that occur to prepare a woman’s body for possible pregnancy. A menstrual cycle is defined as the first day of menstrual bleeding of one cycle to the first day of menstrual bleeding of the next cycle.

Obstetrician–Gynecologist (Ob-Gyn): A doctor with special training and education in women’s health.

Ovulation: The time when an ovary releases an egg.

Progesterone: A female hormone that is made in the ovaries and prepares the lining of the uterus for pregnancy.

Progestin: A synthetic form of progesterone that is similar to the hormone made naturally by the body.

Sexual Intercourse: The act of the penis of the male entering the vagina of the female. Also called “having sex” or “making love.”

Sexually Transmitted Infections (STIs): Infections that are spread by sexual contact. Infections include chlamydia, gonorrhea, human papillomavirus (HPV), herpes, syphilis, and human immunodeficiency virus (HIV, the cause of acquired immunodeficiency syndrome [AIDS]).

Sperm: A cell made in the male testicles that can fertilize a female egg.

If you have further questions, contact your obstetrician–gynecologist.

FAQ114: This information was designed as an educational aid to patients and sets forth current information and opinions related to women’s health. It is not intended as a statement of the standard of care, nor does it comprise all proper treatments or methods of care. It is not a substitute for a treating clinician’s independent professional judgment. Please check for updates at to ensure accuracy.

Copyright May 2019 by the American College of Obstetricians and Gynecologists

American College of Obstetricians and Gynecologists
409 12th Street SW, Washington, DC  20024-2188
Mailing Address: PO Box 96920, Washington, DC 20024-9998