As for how long oral contraceptive pills are effective, short-acting contraceptive pills need to be taken orally every day, 21 or 28 pills in a row, after 7 days of oral contraception will reach 99% of the contraceptive effect, at least after 7 days of coitus without having to take contraceptive measures. However, emergency contraceptive pills are about 80% effective as long as they are taken orally within 72 hours of intercourse, because emergency contraceptive pills are not 100% effective and there is a chance of contraceptive failure. You can buy a pregnancy test about 12 days after intercourse to rule out the possibility of conception. If there is no conception, you can be patient and wait for your period. Contraceptive pills also have certain side effects, it is recommended to observe.