How to Use the Morning-After Pill

Choosing, Using, and Timing Emergency Contraceptive Pills

Emergency contraceptive pills can be taken when you have condomless sex or suspect the birth control method you used may have failed. For instance, maybe you and your partner used an external or internal condom and it broke, you forgot to take several of your birth control pills, or you were late getting your birth control injection.

Emergency contraception can be effective, but it's important to know what's available, how it works, and how soon after sex you need to take it.

Morning-After Pills
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Though most people know them as the "morning-after" pill, this isn't an accurate name since you can use emergency contraceptive pills for three to five days after condomless sex, depending on what you use. One type is available over-the-counter and another is only available with a prescription.


Click Play to Learn About Plan B One-Step Emergency Contraception

This video has been medically reviewed by Chioma Ndubisi, MD


Over-the-counter emergency contraceptive pills include:

Plan B is the brand name and the others are generic forms of the same medication. Each consists of one pill that contains 1.5 milligrams of levonorgestrel, a synthetic version of the hormone progesterone that has been used in many types of birth control pills for years. Levonorgestrel needs to be taken within three days of having sex.


The only emergency contraceptive pill that you need a prescription for is called Ella. This pill contains a substance called ulipristal acetate and you can take it up to five days after having sex.

Daily Birth Control Pills

If you're already on a combination birth control pill (and depending on the pill you're on), you have one more option: taking a certain number of your daily pills, usually four to five, in two doses within 12 hours of each other.

This method may not be as effective as Plan B or Ella, and it may also cause worse side effects. You should talk to your healthcare provider before using this option to make sure it'll work with your prescription, as it doesn't work with all birth control pills.

How They Work

Though it's unclear exactly how emergency contraceptive pills work, evidence shows that they primarily prevent, or at least delay, ovulation so that there's no egg released to be fertilized for several days.

They may also prevent sperm, which can live for up to five days in your body, from fertilizing an egg that has already been released. Lastly, there is some question if they may change the lining of your uterus so that even if an egg does get fertilized, it won't be able to implant in your uterus. That possibility has made these pills a source of major controversy. However, there is evidence that shows this is highly unlikely.

That said, the jury is still out regarding whether or not emergency contraceptive pills, particularly Plan B, actually prevent implantation. Much of the research so far shows that Plan B and its generic equivalents don't have any effect on your uterine lining at all, so they wouldn't prevent a fertilized egg from implanting. In other words, they don't cause an abortion.

Similarly, other studies have shown that while Plan B is very effective when it's taken before ovulation, it's virtually ineffective when it's taken on the day you ovulate or after. This is further evidence that it probably doesn't affect anything that happens after an egg is fertilized.

One thing is certain: Neither type of emergency contraceptive pill will affect an existing pregnancy, medically defined as beginning with implantation. They primarily work to stop or delay ovulation and/or prevent fertilization from happening at all.


With Plan B and other products containing the same drug, timing is key—the sooner after sex you take it, the better it works.

Within 24 Hours Between 48-72 Hours
95% Effective 61% Effective

It may still be somewhat effective for up to five days afterward, depending on where you are in your menstrual cycle.

On the other hand, Ella maintains its efficacy at a steady rate and it's approved for use up to five days after sex. It's about as effective as Plan B for the first 72 hours, but once you pass the three-day mark, Ella is more effective.

Combination birth control pills are considered the least effective method of the three when they're used as emergency contraception. However, they may be a good option if you don't have access to anything else.

Whether emergency contraceptive pills work for you depends in part on two factors.

  • The amount of time that has gone by since you had sex: The sooner you take the pill, the more likely it is to keep you from getting pregnant.
  • The point in your cycle when you had sex: The closer you are to ovulation, the less effective the morning-after pill will be. If you've already ovulated, emergency contraceptive pills won't help.

How to Use

If you find yourself in need of emergency contraception, choosing and using over-the-counter levonorgestrel is easy. Generic versions are just as safe and effective as Plan B but do check the expiration date before buying it.

You can take the pill at any time of day. Again, the sooner after you've had sex, the better. In fact, it may be a good idea to have a package of the morning-after pill on hand so you can use it as quickly as possible if the need arises, rather than take time to go to the store. To make sure it will be effective, store it at room temperature and if you don't use it before it expires, toss it and replace it with a new one.

If it's been close to three days since you had condomless sex or birth control failure, you may want to consider talking to your healthcare provider about getting a prescription for Ella or getting a copper IUD instead.

Do read the directions and package insert first, especially so you know how you may feel after taking this emergency contraceptive. Thousands of people have taken the morning-after pill with no serious complications, though there are some common minor side effects.

Potential Side Effects

You may experience some common side effects of emergency contraceptive pills such as:

  • Nausea or vomiting (you may be able to avoid this by taking an over-the-counter nausea drug an hour before you take the pill)
  • Breast tenderness
  • Headache
  • Pain in the lower part of your abdomen
  • Fatigue
  • Dizziness
  • Spotting or irregular bleeding before your next period
  • Change in timing of your next period
  • Altered flow during your next period (heavier or lighter)

If any unexpected adverse reactions occur after using the morning-after pill, you should call your healthcare provider. You may also want to consult with your practitioner if your scheduled period is more than seven days late, as this could indicate that you're pregnant.

Risk of Ectopic Pregnancy

Some studies have reported an increased risk of ectopic pregnancy, in which a fertilized egg implants somewhere other than your uterus, in people with vaginas taking levonorgestrel. Ectopic pregnancy is a medical emergency.

However, not all researchers agree about the risk. A 2010 review of literature on the subject concluded that the risk of ectopic pregnancy was no greater with emergency contraception than in any other circumstance. Since then, though, ectopic pregnancies have continued to be reported. A 2018 safety profile study states that while a causal relationship between levonorgestrel and ectopic pregnancy isn't established, the number of known cases suggests that there could be an association.

Symptoms of an ectopic pregnancy include:

  • Vaginal bleeding
  • Shoulder pain
  • Abdominal pain
  • Weakness
  • Dizziness

If you develop any of these three to five weeks after using the morning-after pill, see your healthcare provider right away. This is a potentially life-threatening condition that requires immediate medical treatment.

How Long They Last

If an emergency contraceptive pill prevented you from getting pregnant, it has done its job. Remember that the pill won't continue to prevent pregnancy after that one instance. After you use it, your fertility will return, so don't take a chance and have condomless sex. And remember that emergency contraceptive pills don't protect you from STIs.

You can use Plan B more than once during the same month, but you should only use Ella once per menstrual cycle; otherwise, its effectiveness can be decreased.

A Word From Verywell

Don't treat emergency contraceptive pills as a regular form of birth control. For one thing, they're not as reliable as other options. For another, your periods could become irregular and unpredictable and you may have more unpleasant side effects since you're exposing yourself to higher hormone levels.

These pills can also end up being a lot more expensive than regular birth control. Talk to your healthcare provider about the best birth control option for you.

11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. U.S. Department of Health and Human Services. Emergency contraception.

  2. Jadav SP, Parmar DM. Ulipristal acetate, a progesterone receptor modulator for emergency contraception. J Pharmacol Pharacother. 2012;3(2):109-111. doi:10.4103/0976-500X.95504

  3. Princeton University, Office of Population Research. Combined Emergency Contraceptive Pills ("Morning After Pills").

  4. Matyanga CM, Dzingirai B. Clinical pharmacology of hormonal emergency contraceptive pillsInt J Reprod Med. 2018;2018:2785839. doi:10.1155/2018/2785839

  5. Berger C, Boggavarapu NR, Menezes J, Lalitkumar PG, Gemzell-Danielsson K. Effects of ulipristal acetate on human embryo attachment and endometrial cell gene expression in an in vitro co-culture system. Hum Reprod. 2015;30(4):800-811. doi:10.1093/humrep/dev030

  6. Batur P, Kransdorf LN, Casey PM. Emergency contraception. Mayo Clin Proc. 2016;91(6):802-807. doi:10.1016/j.mayocp.2016.02.018

  7. American College of Obstetricians and Gynecologists. Emergency contraception.

  8. Steele BJ, Layman K. Ectopic pregnancy after Plan B emergency contraceptive use. J Emerg Med. 2016;50(4):663-6. doi:10.1016/j.jemermed.2015.11.011

  9. Cleland K, Raymond E, Trussell J, Cheng L, Zhu H. Ectopic pregnancy and emergency contraceptive pills: a systematic review. Obstet Gynecol. 2010;115(6):1263-1266. doi:10.1097/AOG.0b013e3181dd22ef

  10. Kurian A, Kaushik K, Subeesh V, Maheswari E, Kunnavil R. Safety profile of levonorgestrel: A disproportionality analysis of Food and Drug Administration Adverse Event Reporting System (FAERS) Database. J Reprod Infertil. 2018;19(3):152-156.

  11. Sivalingam VN, Duncan WC, Kirk E, Shephard LA, Horne AW. Diagnosis and management of ectopic pregnancyJ Fam Plann Reprod Health Care. 2011;37(4):231-240. doi:10.1136/jfprhc-2011-0073

Additional Reading

By Dawn Stacey, PhD, LMHC
Dawn Stacey, PhD, LMHC, is a published author, college professor, and mental health consultant with over 15 years of counseling experience.