Emergency Contraceptive Pills (ECPs)

One yellow pill.

The emergency contraceptive pill (ECP), more commonly known as Plan B or “the morning-after pill,” can be used to prevent pregnancy after unprotected sex or the failure of a primary birth control method. The name “morning after” is misleading: it can (and should) be taken sooner than the morning after or a few days after intercourse. The emergency contraception pill is not an abortion pill and cannot interfere with an existing fetus or induce abortion if conception has already occurred. ECPs merely delay ovulation so that the female’s ovary takes longer to release the egg than usual. This prevents the sperm and the egg from meeting, and fertilization will not occur. While safe to use in emergency situations, ECPs should not be relied on as a regular form of birth control. ECPs are not as effective as birth control in the long-term and may become quite expensive with repeated use. You can find the various forms of ECPs at your local drugstore or health clinic. You can take ECPs even if you have been previously pregnant or plan on becoming pregnant in the future.

To find a clinic near you that provides ECPs, or for more information, contact the Emergency Contraception Hotline at 1-800-584-9911. To find your local Planned Parenthood (another information resource for ECPs), call 1-800-230-PLAN.

How Do They Work?

The "ellaOne" emergency contraception pill next to a glass of water.

Emergency Contraceptive pills are not an abortion pill (also called medication abortion or RU-486).1 They cannot terminate an existing pregnancy—they simply prevent a conception from occurring.2 If you are already pregnant, the ECP will not harm the pregnancy.3 This means they do not work if you take them prior to unprotected intercourse and instead work best immediately after intercourse. This is because sperm can live inside the vagina and fallopian tubes for up to five days. If an egg becomes mature and travels through the fallopian tube during these five days of sperm vitality, the egg can be fertilized and implant itself on the vaginal walls resulting in pregnancy. Emergency contraceptive pills work differently depending on which phase of the menstrual cycle you are in and how soon you take the ECP after intercourse. If ovulation (the process of an ovary releasing a mature egg) has not yet begun, the ECP will prevent the ovary from releasing the matured egg. If ovulation has already occurred, an ECP will inhibit the implantation of the fertilized egg onto the vaginal walls. This implantation prevention method is a less common occurrence so effectiveness of an ECP will decrease if ovulation has already occurred.2

What Types are Available?

Females have a range of options when deciding which ECP is best for them. Currently, there are three different types of emergency contraceptives available:

  • Progestin-Only Pills contain levonorgestrel, which can either delay ovulation or prevent fertilization in order to minimize the risk of pregnancy if taken within 5 days of unprotected sex.4 These pills lose effectiveness as time elapses but can reduce the risk of pregnancy by up to 88% if taken within the first 24 hours after unprotected sex.5 Some examples of progestin-only pills include Plan B One-Step, Next Choice, and Levonorgestrel Tablets. Some brands have one pill, and others have two. Levonorgestrel that contains two pills with 0.75 mg levonorgestrel each may direct users to take the second dose 12 hours after the first; however, recent studies have shown that taking both 0.75 mg doses at once is just as effective and causes no additional side effects when compared to two 0.75 mg doses taken 12 hours apart.6
    • The i-pill is a common progestin-only ECP that is used outside of the United States. The i-pill must be taken within 72 hours of unprotected sex to prevent pregnancy and is more effective the sooner it is taken.7
  • Anti-Progestin Pills contain either ulipristal acetate or mifepristone and are found to be even more effective than progestin-only pills. This ECP affects how progesterone works in your body by delaying or preventing ovulation.4 These pills can be taken up to 5 days after unprotected sex and (unlike progestin-only pills) are equally as effective at preventing pregnancy for all 5 days.
  • Combination Pills (“combo pills”) contain both progestin and estrogen and can be used as a form of emergency contraception, usually with the second dose taken 12 hours after the first.8 This type of ECP contains the same hormones as regular birth control pills but in much higher doses.4 This mode of emergency contraception is more likely than progestin-only methods to cause adverse side effects, such as nausea. Combination pills also put females with a history of blood clots, strokes, or migraines at greater health risks (including an increased risk in heart disease and blood clot formation) than progestin-only pills. Researchers currently recommend progestin-only pills over combination pills for use as emergency contraception.9

The Copper IUD as an Emergency Contraceptive

An intrauterine device.

Another form of emergency contraception is the copper intrauterine device (IUD). It is more effective than the emergency contraceptive pills.3 The copper IUD is a non-hormonal contraceptive (immobilizing sperm so they cannot swim as well10) that can prevent pregnancy if inserted by a healthcare practitioner within five days of unprotected sex. Though non-hormonal, the copper IUD can alter menstrual cycles, causing some to be heavier and more painful.10 The copper IUD can then remain in place to prevent pregnancy for up to 10 years, acting with 99% effectiveness at preventing pregnancy. The risks of the copper IUD include getting a pelvic inflammatory disease (PID) and perforation of the uterine walls, though these cases are extremely rare (2 cases out of 1,000 users). If there is a high likelihood of a Sexual Transmitted Disease (STI)—as there are with sexual assault cases or for certain women—it is advised to use a different form of emergency contraception.3 Though the IUD has a relatively high up-front cost ($500-$900)10, there are no ongoing costs, and it requires only monthly thread checks by the user. Many healthcare centers will accept insurance, which may lower the cost of this contraception method.10

How Do I Use ECPs?

If you plan on using ECPs, it is wise to consult a doctor or pharmacist to learn of any side effects you may experience. These side effects of ECPs may include, but are not limited to, changes in your period, nausea, lower abdominal pain, fatigue, headache, dizziness, and breast tenderness.4 If vomiting occurs after swallowing the emergency contraceptive pill(s), contact a doctor immediately to see if a repeat dose is necessary. Typically, if you throw up within 2 hours after ingestion, you should take the pill again.3

Some ECPs come in two high-dose pills, while Plan B One-Step is only one high-dose pill. Both types of ECPs are effective at preventing pregnancy if taken properly. With the two-pill system (such as Next Choice), one pill is taken within 3 days (with a limit of up to 5 days) after unprotected sex, and the second pill is taken 12 hours after the first. However, studies have shown that it is just as effective to take both 0.75 mg levonorgestrel pills at once as opposed to separating the doses by 12 hours.6 With the one-pill system, only one pill is taken within five days after unprotected sex (the sooner the better!).3 You should begin your period within 10-12 days of taking ECPs. For some women, it could take as long as three weeks. If it has been longer than that, we recommend you take a pregnancy test.10 For progestin-only (Plan-B One Step) and combo pills, you may resume using your hormonal birth control immediately after using ECPs, but be sure to use a barrier method until your next period. Anti-progestin pills (ella) require that you to wait resume hormonal birth control until five days after using an ECP.4


When taken as directed, ECPs are highly effective at preventing pregnancy. ECPs are most effective within the first 72 hours (3 days) after unprotected sex, but still retain some efficacy up to 5 days after unprotected sex. When taken within 24 hours of unprotected sex, ECPs are about 90% effective at preventing pregnancy. When taken about 72 hours after unprotected sex, progestin-only ECPs (both one-pill and two-pill brands) are about 89% effective at preventing pregnancy. Combined pills reduce the risk of pregnancy by about 75%.5,8 The copper IUD, when used as an emergency contraceptive, is about 99% effective at reducing pregnancy risk and can be left in place to provide ongoing contraception for up to 10 years.3 Since none of these methods are perfect, it is recommended to take a pregnancy test a few weeks after taking ECPs to ensure that pregnancy has not occurred.


The cost of ECPs can range anywhere from $10 to $70. The variation in cost depends on the type of pill, insurance coverage, your age, and your location.11 ECPs are generally less expensive at family planning clinics like Planned Parenthood, which sometimes offers ECPs for free. If you currently attend a university, your student health may offer lower prices. Check with your local Planned Parenthood to learn more about how to get ECPs: 1-800-230-PLAN.

Which Option is Best for Me?

There are various types of emergency contraception from which you can choose. Refer to the below chart to compare the four types:

Method Pros Cons
Plan B (Progestin-Only) No prescription regardless of age and gender10 One-step pill Can resume using hormonal birth control immediately after (but be sure to use a barrier method until next period)4 Hormonal side effects Reduced effectiveness as days go by10
ella (Anti-Progestin) Same effectiveness on day 5 as day 110 One-step pill Need to obtain a prescription10 Less effective if taking hormonal birth control within five days of taking ella10 Must wait five days to resume using hormonal birth control again (and must use barrier method until next period)4
Combination Pills Same hormones as combination birth control6 Can take this even if you cannot usually take hormonal birth control Can resume using hormonal birth control immediately after (but be sure to use a barrier method until next period)4 More likely to get adverse side effects (nausea, headache, dizziness, ect.)6 Usually taken in two doses Less effective than progestin-only pills
Copper IUD Most effective Same effectiveness on day 5 as day 1 Will protect you for up to 10 years after insertion5 No further work on your part (just check for a string every month) Non-hormonal, so no hormonal side effects Difficult to obtain an emergency appointment in time Expensive: $500-$900 USD Heavier, more painful periods in some cases12 Some cases of perforation and pelvic inflammatory disease (PID)5

The four varieties of emergency contraception offer you a chance to find what method works best for you. Some methods such as the copper IUD and ella are just as effective on day 5 as they are on day 1, so if it has been four days since unprotected intercourse, these methods will be more effective for you. Other methods such as Plan B are less expensive and are easily obtained over the counter without any prescription. You can always contact your doctor to see which method would work best for you, especially if you are taking any other forms of medication that could negatively interact with these emergency birth control methods.

Advantages of Emergency Contraceptive Pills

A variety of contraceptive methods, including a condom, intrauterine device, birth control pills, and arm implant.

Emergency contraception is a harmless, yet extremely effective method for females to use if they believe they may be faced with an unwanted pregnancy. There are several advantages to using emergency contraception:

  • They are a safe way to prevent pregnancy after unprotected intercourse.
  • They are highly effective at preventing pregnancy if used within 72 hours (3 days)
  • They can be taken privately and discretely.
  • Plan B One-Step is available over the counter without a prescription regardless of age. No government-issued identification card is required for purchase. Other types of ECPs can be purchased without a prescription if you are over the age of 17 (in the United States).10
  • ECPs are NOT abortion pills; they simply interfere with fertilization and/or implantation.10
  • Combo pills and progestin-only pills (Plan-B One Step) allow you to resume using your hormonal birth control immediately after using ECPs (but be sure to also use a barrier method until your next period).4

ECPs are a great back-up emergency contraceptive if your primary birth control has failed. They are usually very effective if taken immediately, relieving you of any worry surrounding a potential and unwanted pregnancy.

Disadvantages of Emergency Contraceptive Pills

Although emergency contraception is an effective method for preventing pregnancy after intercourse has occurred, there are some issues females could encounter. There are several disadvantages to using emergency contraception:

  • They do not protect against HIV or STIs.4
  • They are not effective if conception has already occurred.10
  • They can be expensive.
  • A prescription may be required if using ella or if under the age of 17 years old (not required for Plan B One-Step).10
  • Side effects such as nausea, headache, dizziness, and breast tenderness may occur.10
  • Not recommended to be used if you have already used ella since your last period.

Like other forms of birth control, ECPs cannot protect against STIs or terminate an existing conception. The hormones most ECPs contain can give undesirable side effects and usually alter your menstrual cycle.

Availability of Emergency Contraceptive Pills in the U.S.

As of April 2013, Plan B One-Step has been approved for over-the-counter sale to individuals of all ages in the United States without a prescription or government-issued identification card. Before this law took effect, the previous age requirement without a prescription was 17. Those under 17 years of age could only receive Plan B One-Step with a prescription from their healthcare provider.13

If you are required to obtain a prescription for ECPs (such as ella), it is necessary to contact a doctor. ECPs are only prescribed to females, so males under the age of 17 cannot receive a prescription from their healthcare provider. If a male is over the age of 17, he can purchase ECPs with proof of age. If visiting a new medical clinic, be sure to provide a complete medical history to prevent any potential problems you may otherwise experience with the ECP. If you believe you will use ella in the future, it is best to go to your doctor and get a prescription so you can have them on hand in case of an emergency. If you wait until after having unprotected sex, you can buy ella using an online prescription. However, we recommend having it readily available beforehand.10 When obtaining the ECP over the counter at drugstores with a licensed pharmacist, be sure to bring a government-issued identification card with your proof of age. To find a pharmacy that provides ECPs near you, contact the Emergency Contraception Hotline at 1-800-584-9911 or Planned Parenthood at 1-800-230-PLAN.

Incorrect Ways to Use ECPs

Emergency contraception is only 95% effective when used correctly. To ensure that emergency contraception is being used effectively, there are several things to keep in mind:

  • When you are already pregnant—ECPs are not an abortion pill10
  • Mixing different kinds of ECPs (ella and Plan B) at once—they will counteract each other10
  • Using multiple hormonal birth control pills—just because the ECPs contain higher doses of hormones than normal hormonal birth control pills does not mean that they replicate the effects of ECPs9
  • Using an ECP prior to sexual intercourse—ECPs only prevent pregnancy after intercourse has occurred4
  • Taking ECPs multiple times since your last period—although this is not medically a concern10, the amount of hormones these pills provide will deregulate your menstrual cycle by throwing off your hormonal balance
  • Using an ECP more than 5 days after unprotected intercourse—ECPs are only effective up to 5 days after intercourse. After that point the sperm with the potential to fertilize an egg are no longer alive

Emergency contraception will not be effective if you use multiple ECPs at once or use several hormonal birth control combination pills as both methods will introduce too many hormones into the system in the improper ratios. Emergency contraception, again, is not an abortion pill so it cannot be used to terminate an existing conception. ECPs also are only effective after intercourse, and therefore should not be used prior to unprotected sex.

ECPs Are Not a Primary Form of Birth Control

Emergency contraceptive should not be used as your primary method of birth control. This is due to the following reasons:

  • The morning-after pill is less effective than hormonal forms of birth control8
  • Repeated use can become very expensive
  • The hormonal increase can change your menstrual cycle or cause annoying side-effects such as nausea.

Emergency contraception, though medically harmless to your body even with repeated uses14,15, should not be used as your primary form of birth control because they can alter your menstrual cycle, will become expensive, and are less reliable than other hormonal birth control methods.

When Should I Use ECPs?

Two nude bodies hugging.

If you are uncertain about whether or not you should use emergency contraception, refer to the breakdown below. The breakdown includes various sexual encounters and the corresponding chance of pregnancy—from low to high. A low chance of pregnancy means you should not worry about taking emergency contraception, while a high chance of pregnancy urges you to take one. We encourage you to use your discretion if your sexual encounter is a “medium risk” situation. If you are worried about a very specific sexual encounter, please write into our Sexperts!

Low Chance of Pregnancy: You Don’t Need to Take One

If you engaged in any of the following sexual activities, there is no chance that you are pregnant, so you should not take an emergency contraceptive:

As long as there was no penile-vaginal penetration and no bodily fluids were exchanged (this includes pre-cum which is pre-ejaculate that is produced prior to ejaculation), then there is no reason to worry about a potential pregnancy, and you do not need to take an emergency contraceptive. If you are already pregnant, there is also no reason to take an emergency contraceptive as it is not an abortion pill and cannot terminate an established conception (i.e. pregnancy).

Medium Chance of Pregnancy: You Should Consider Taking One

If you engaged in any of the following sexual activities, there is a chance that you are pregnant, so you should use your discretion when deciding whether or not to take an emergency contraceptive:

If you participated in safe sex but are worried about other factors (i.e. your menstrual cycle, one form of birth control failed, when ejaculation occurred) may have caused pregnancy, you should consider taking an emergency contraceptive after carefully analyzing your situation.

High Chance of Pregnancy: We Recommend You Take One

If you engaged in any of the following sexual activities, there is a high chance that you are pregnant and should take an emergency contraceptive:

If you engaged in penile-vaginal intercourse, especially without another form of birth control, there is a high chance that you are pregnant and should take an emergency contraceptive.3,10

Concluding Remarks

If you are worried that you might be pregnant, there are several methods of emergency contraception available to you. A copper IUD is just as effective on day 5 as is it on day 1 and will continue to protect you for up to 10 years or whenever you decide to remove it. Though the upfront cost is expensive ($500-$900), there are no ongoing costs and insurance may reduce the price. Plan-B One Step is a popular choice since there is no prescription required, but be sure to use this as soon as unprotected intercourse occurs because its effectiveness will decrease as the days go by. Like the Copper IUD, ella is as effective day 5 as it is day 1, but it requires a prescription, so it is best for you to visit a doctor and have some on hand in case of an emergency. Combination pills are also available, but are the least effective method.

All ECPs are 90% effective if taken within 24 hours of intercourse, but note that this is not as effective as primary birth control, so it is not recommended to use emergency birth control as your primary form of birth control. Finally, ECPs should not be used prior to intercourse, if you are already pregnant, or after 5 days of intercourse. Different methods work best depending on your circumstances, so be sure to figure out what will work best for you, and be sure to practice safe sex.

If you would like a simple  recap of the article, please refer to this video made by Planned Parenthood below comparing Plan B and ella.


  1. Parenthood, Planned. “What Kind of Emergency Contraception Is Best For Me?” Planned Parenthood. 2018.
  2. “Plan B One-Step®: Home.” Plan B One-Step®: Home. Women’s Capital Corporation, 2013.
  3. “Emergency Contraception.” WHO. N.p., June 2017.
  4. “Emergency Contraception.” Women’s Health Care Physicians. American College of Obstetricians and Gynecologists. October 2015.
  5. “Emergency Contraception: Progestin-only Pills as Emergency Contraceptives.” Princeton University, 14 August 2017.
  6. “EC Methods.” Association of Reproductive Health Professionals, March 2011.
  7. “i-pill—Uses, Side Effects, Precautions to be Taken While Using…” HealthClues, 8 January 2018.
  8. “Emergency Contraception: Combined pills as emergency contraceptives.” Princeton University, 14 August 2014.
  9. “Combination » Choices Pregnancy Services.” Combination » Choices Pregnancy Services. 2012.
  10. “Plan B One-Step®: Home.” Plan B One-Step®: Home. Women’s Capital Corporation, 2013.
  11. “Emergency Contraception: Progestin-only Pills as Emergency Contraceptives.” Princeton University, 14 August 2017.
  12. “Can You Get Pregnant With Precum?” American Pregnancy Association, 2 Jan. 2018.
  13. Fecteau, Jessica. “Plan B Emergency Contraceptive Changes Age Requirement for Purchasing Pill.” Central Michigan Life. 17 Apr. 2013.
  14. Parenthood, Planned. “How could anal sex cause pregnancy?” Planned Parenthood, 19 July 2012.
  15. Jasem C. “A Prospective, Open-label, Multicenter Study to Assess the Pharmacodynamics and Safety of Repeated use of 30 mg Ulipristal Acetate.” PubMed. U.S. National Library of Medicine National Institutes of Health. January 2016.
  16. “Can You Get Pregnant on Your Period?” American Pregnancy Association, 2 Sept. 2016.
  17. Parenthood, Planned. “Can you get pregnant the first time you have sex?” Planned Parenthood, 14 October 2010.

Last Updated: 16 February 2018.