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What are Emergency Contraceptives?



Emergency contraceptives prevent pregnancy after unprotected sex, failed birth control, or sexual assault. They’re often called “morning-after pills” or “plan b.” There are two different kinds of emergency contraceptives: emergency contraceptive pills and the copper intrauterine device (IUD).

Emergency contraceptives prevent pregnancy, but they do not cause abortions[1]. They prevent pregnancy by preventing fertilization of an egg[2]. They can thicken cervical mucus, which forms a barrier that prevents sperm from reaching an egg. They also prevent pregnancy by delaying ovulation, which is the release of an egg from an ovary.

Because emergency contraceptives only prevent pregnancy, they will not work if you are already pregnant. They also won’t protect you from getting a sexually transmitted infection (STI).

Under the Affordable Care Act, most insurance companies are required to cover emergency contraception[3]. If your insurance covers emergency contraception, it will be free (no co-pay). Some insurance plans cover emergency contraception without a prescription. Other insurance companies require a prescription. Some states let pharmacists prescribe emergency contraception in the pharmacy, without a physician’s prescription. Those states are Alaska, California, Hawaii, Maine, Massachusetts, New Hampshire, New Mexico, Vermont, and Washington.

What are the Different Emergency Contraceptives


1. Pills with progestin (levonorgestrel)

Plan B One-Step, Next Choice, AfterPill, and many others only contain progestin. These pills should be taken within 3 days of unprotected sex. They work better the sooner you take them. You can take them up to 5 days after, but their effectiveness decreases each day. They aren’t nearly as effective after 4 or 5 days[4].

You can find these pills on the shelves at drug stores like CVS. The cost ranges from about $35 to $50. Anyone can buy these pills, regardless of age, without a prescription, and without needing to show an ID. If you have a prescription, your insurance can cover this fee for you.

You can also find these pills online for about $25 at This website is recommended by several major university health centers including the emergency contraceptive website by Princeton University and the Association of Reproductive Health Professionals. You can also buy these pills online at, but they are more expensive. You might want to consider ordering these pills online, before you need them, as a backup. Since they are most effective if taken as soon as possible, you may want them on hand. It may take longer than 3-5 days for the emergency contraception pills to ship, or your nearest pharmacy might be closed when you want to buy them.  Emergency contraption pills don’t expire for several years, but you should be aware of the expiration date if you’re buying them for possible future use.

If you have unprotected sex after taking emergency contraception, it will not protect you against getting pregnant. After taking one of these progestin-based pills, you should continue your regular birth control method and use a barrier method (like a condom or diaphragm). Diaphragms with spermicide are more effective than condoms at preventing pregnancy, but condoms have the added benefit of preventing sexually transmitted infections in addition to pregnancy. If you took emergency contraception because of a birth control failure, a barrier method will protect you as you re-start a birth control method. A barrier method will also protect you against STIs, which no other forms of birth control can do.

If you have a body mass index (BMI) over 25, this type of emergency contraceptive might be less effective for you. Some studies have found that the copper IUD and ulipristal acetate pills are more effective at preventing pregnancy in women with a BMI over 25[5]. An example of a BMI over 25 is if you are 5’5” and weigh 151 or more. You can check what your BMI is here.

You should not take more than one type of emergency contraceptive pill within 5 days. They can interact with each other and become less effective.


2. A pill with ulipristal acetate.

Currently there is only one brand that contains ulipristal acetate instead of the hormone progestin: ella. ella is effective up to 5 days after unprotected sex. Unlike progestin-based pills, ella is just as effective at preventing pregnancy on the fifth day after unprotected sex as it is on the first day.

In the U.S., you need a prescription to get ella at a pharmacy but you can also order it online at KwikMed or at prjktruby. These sites are also recommended by major university health centers. Without insurance, ella normally costs between $50 and $75. Anyone with a prescription can buy ella, regardless of age. Again, you may want to order it online as a backup since it could take more than 5 days to be shipped to you. Some doctors might write you a prescription for ella, just in case you need it in the future.

If you have a BMI over 25, some studies have suggested that ella might be more effective for you than taking a progestin-based emergency contraceptive[5].

ella has not been tested for safety in mothers who are breastfeeding. If you are breastfeeding, you should take a progestin-only emergency contraceptive pill, which is considered safe for women who are breastfeeding.

After taking ella, you should use a barrier method (like a condom or diaphragm) if you have sex again.


Diaphragms with spermicide are more effective than condoms at preventing pregnancy, but condoms have the added benefit of preventing sexually transmitted infections in addition to pregnancy. If you usually take hormonal birth control, like the pill, you should wait 5 days after taking ella before resuming your birth control. The hormones in the birth control pill can make ella less effective.

As mentioned earlier in this article, you should not take more than one type of emergency contraceptive pill within 5 days.

3. Copper IUD

The copper IUD is the most effective emergency contraceptive (over 99% effective), no matter what your weight is. The IUD fits inside your uterus and requires a medical professional to insert. You can get a copper IUD inserted up to 5 days after unprotected sex or birth control failure. The copper IUD works for up to 12 years once inserted and prevents sperm from fertilizing an egg.

How Effective are Emergency Contraceptive Pills?


It is not possible to determine exactly how effective these pills are since they prevent something that hasn’t happened yet and might not have happened even without using emergency contraception. Emergency contraceptive pills are predicted to prevent about 55-85% of pregnancies after unprotected sex. Experts estimate that progestin-based pills prevent 7 out of every 8 pregnancies that would be expected if an emergency contraceptive was not used. Experts estimate that ella prevents 6 to 7 out of every 10 expected pregnancies, which makes it slightly less effective, although it is more effective on the 4th and 5th days after unprotected sex [6].

If your period is delayed by more than one week after taking an emergency contraceptive pill, you should be speak with your healthcare provider.

How Many Times Can I Use the Morning-After Pill?


You can take the morning-after pill whenever you need to, but you should not use it as a regular form of birth control. Morning-after pills are not as effective as non-emergency birth control methods. Plus, they are expensive and they can cause unpleasant side effects.

Are There Any Side Effects?


Emergency contraceptives can cause nausea, vomiting, headache, breast tenderness, cramps, and fatigue. These side effects usually go away within 24 hours but sometimes last a few days. If you vomit within 1 hour after taking a progestin-based emergency contraceptive pill, you should contact your healthcare provider to find out if you should take another dose to be sure it will be effective. Remember that repeated use of ella in the same menstrual cycle isn’t recommended because the safety is unknown. You should also contact your healthcare provider if side effects don’t go away within a few days.

Women with preexisting medical conditions such as cardiovascular disease, migraines, liver disease, or previous ectopic pregnancy may use emergency contraceptives. In fact, research has shown that pregnancy poses a greater threat than emergency contraception to women with medical problems such as blood clots and liver disease.

Information about emergency contraceptives is easy to find: go to for more information or to find an emergency contraceptive provider near you. This university web site has no connection to or funding from any of the companies that make emergency contraception.


  1. Office of Population Research at Princeton University. (2017). Emergency Contraception Website. Retrieved from Accessed on October 4, 2017.

  2. Trussell, James and Kelly Cleland. (2012). Emergency contraception: How it works (how it doesn’t). Science Friday. Retrieved from

  3. U.S. Centers for Medicare & Medicaid Services. (2017). Birth Control Benefits. Retrieved from Accessed on October 4, 2017.

  4. Association of Reproductive Health Professionals. Clinical proceedings: Update on emergency contraception. (2011). Retrieved from: Accessed on October 4, 2017.

  5. Jatlaoui, T., Curtis, K. Safety and effectiveness data for emergency contraceptive pills among women with obesity: a systematic review. (2016). Contraception 94;605-611.

  6. Office of Women’s Health. (2012). Birth Control Guide. In U. S. Food and Drug Administration (Ed.).

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