The morning-after pill refers to the emergency contraceptive pill, which is required to be taken within 72 hours of sex and is more effective the earlier it is taken. However, the pill is only effective for a single sexual intercourse and may cause contraceptive failure for multiple sexual intercourses within 72 hours. Contraceptive pills are divided into emergency, short-acting, and long-acting pills according to their duration of action, and the period of time for taking contraceptive pills with different durations is different. If the pill is effective only for this act after sex, it should be used, and it is generally recommended that it be used within 24 hours for best results. However, emergency contraceptive pills can have side effects on women, such as nausea and vomiting, and can also cause irregular menstruation and even affect a woman’s pregnancy. Therefore, the emergency contraceptive pill is not recommended as a regular means of birth control and is generally taken at most 1-2 times a year. If a woman does not want to get pregnant, the best contraceptive method is to use birth control ring or condom, which is more effective and not more harmful to the body.