Emergency contraceptive pills are also generally effective the day after intercourse, but there is a risk of contraceptive failure. The emergency contraceptive pill is an emergency remedy for unprotected sex and can be used under medical supervision. It is generally effective when taken within 72 hours of unprotected sex, so it is also effective when taken the day after intercourse, but there is still a risk of contraceptive failure, and when menstruation is overdue for more than 1 week, you need to seek medical attention to rule out the possibility of pregnancy. Because emergency contraceptive pills have a high dosage and can cause adverse reactions such as nausea, vomiting and irregular vaginal bleeding, they are not recommended as a regular contraceptive measure. Women who do not wish to have children can take safe and effective contraceptive measures under the guidance of a doctor.