Emergency contraception is most effective when used as soon
as possible after
unprotected sex, but may be effective up to 120 hours after the fact. Studies indicate that use of emergency contraception prevents up to 75% of expected pregnancies.
There are very few people who can
not take emergency contraception. Even women who are not normally can
didates for oral contraceptives, such as those with migraines, liver disease, or heart disease can
take emergency contraception.