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Answers to Frequently Asked Questions About…

How to Use Emergency Contraception

How long do I have after sex to take emergency contraceptive pills?

If you have sex without using other contraception, your regular birth control fails, or you are made to have sex against your will, take action right away to learn what your options are. Even though emergency contraception is often called the “morning after pill” or “day after pill,” it may be effective for up to 5 days (120 hours) after unprotected sex.

In the United States, there are two different kinds of emergency contraceptive pills available: ulipristal acetate (ella) and progestin-only (like Plan B One-Step, Next Choice One Dose, My Way).


ella is a prescription-only product. It is more effective than progestin-only EC, particularly on the 5th day after sex. ella is more likely to work when taken closer to ovulation than progestin-only pills; this is important because women have the highest chance of getting pregnant, and are most likely to be having sex, immediately before the egg is released. In clinical studies, the effectiveness of ella did not decline over a 5-day period; however, what’s important for each individual woman is where is you are in your menstrual cycle (how close you are to ovulation). If you are close to ovulation, EC may not be able to prevent pregnancy if you wait 5 days. Therefore, the best thing to do is take EC as soon as you can get it.


Progestin-only EC (like Plan B One-Step and My Way) is now available directly on the shelf (check the family planning aisle) for women and men of any age – you don’t need to show ID. Studies show that progestin-only EC may be effective only through 4 or 5 days after sex.


Click here for more detailed instructions for using daily birth control pills as emergency contraception.


Another excellent option for emergency contraception is the copper IUD (sold in the United States as ParaGard). The copper IUD can be inserted up to 5 days after unprotected sex, and is 99.9% effective at preventing pregnancy after sex. It can be left in place for up to 10 years of highly effective ongoing contraception. You’ll need to have an IUD inserted by a trained healthcare provider, so call your provider right away if you’d like to get an IUD for EC.


A thorough and up-to-date academic review of the medical and social science literature on emergency contraception, including research showing that emergency contraceptive pills can be used up to 120 hours after sex, is available in English and Spanish.

To find health care providers, including pharmacists, who offer emergency contraception in your area, click here.


This website is operated by the Office of Population Research at Princeton University and has no connection with any pharmaceutical company or for-profit organization.

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