It is important to note that EC is not effective if you are already pregnant. EC consists of a specific birth control pills that contain the hormones progestin and estrogen. EC differs from birth control pills in the way that you take them. With birth control pills, one pill is taken once a day, and the small amount of continuous hormones prevents ovulation. When used as EC, these hormones disrupt the natural hormone patterns necessary for pregnancy.
Some evidence also suggests that the hormones change the lining of the uterus.
EC is less effective than a continuous or pre-planned method of birth control, but they are the most effective method available after you have had unprotected intercourse. EC must be used no later than 3 days or 72 hours after unprotected sex or effectiveness is greatly reduced. Your provider will give you a package of 5 Alesse pills to take now and 5 more to take in exactly 12 hours. Most young women can use emergency contraception. Make sure to tell your health care provider if you have ever had unexplained vaginal bleeding, a stroke, blood clots in your legs or lungs, unusual headaches or medical problems like liver disease.