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The Emergency Contraception Website - Your website for the "Morning After"

Answers to Frequently Asked Questions About…

How Emergency Contraception Works

How are emergency contraceptive pills different from the abortion pill (Mifeprex, also referred to as RU-486)?

The abortion pill, also known as mifepristone or RU-486 ("medical abortion" or "medication abortion"), is a different drug from ellaPlan B One-Step, Take Action,  Next Choice One Dose, My Way and Levonorgestrel Tablets, which are approved for sale as emergency contraception in the United States. Emergency contraceptive pills (also called “morning after pills" or "day after pills") prevent pregnancy primarily, or perhaps exclusively, by delaying or inhibiting ovulation; they do not cause an abortion.  For more about how emergency contraceptive pills work, read this comprehensive academic review of emergency contraception.


Mifepristone, which is sold in the United States under the brand name Mifeprex, works differently from levonorgestrel (Plan B One-Step, Take Action, Next Choice One Dose, or My Way) or ulipristal acetate (ella) emergency contraceptive pills. When given after a pregnancy has started, mifepristone stops the development of a pregnancy (which happens once a fertilized egg implants in the uterus). This drug is approved for use in early abortions in the United States, and many other countries. At a far lower dose, mifepristone has been shown to also be effective for preventing pregnancy, like emergency contraceptive pills, but it is only available for this use in China, Russia, Armenia and Vietnam.

For more information about medical abortion, including which countries have approved it, click here. There is also another website that can help you find an abortion provider near you.




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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