We continue to hold the same belief as the U.S. Food and Drug Administration (FDA), which states that there are no safety concerns that preclude the use of levonorgestrel emergency contraceptives in women generally, and continue to believe that all women, regardless of how much they weigh, can use Plan B to prevent unintended pregnancy following unprotected sex or contraceptive failure. The most important factor affecting how well Plan B works is how quickly it is taken. When Plan B emergency contraception is taken as directed, within 72 hours after unprotected sex or birth control failure, it can significantly decrease the chance that a woman will get pregnant. In fact, the earlier the product is taken after unprotected intercourse, the better it works.
Emergency contraception is not meant to be used as a regular form of birth control because it is not as effective. If you find that you are using Plan B frequently, talk to your doctor about finding a primary birth control method that is right for you.