Levonelle

Levonorgestrel is a hormonal medication which is used in a number of birth control methods.[5] It is combined with an estrogen to make combination birth control pills.[6] As an emergency birth control, sold under the brand name Plan B among others, it is useful within 72 hours. This should not be confused with EllaOne which can be effective within 120 hours (5 days) of unprotected sex.[5] The more time that has passed since sex, the less effecti... [wikipedia]