Under normal circumstances, emergency contraceptive pills are effective when taken within 72 hours of sexual intercourse, and are more effective when taken early. You should take the pill empty and avoid eating 2 hours before and after taking it to avoid affecting the absorption of the pill. The emergency contraceptive pill is a contraceptive method for women who have sex without taking any protective measures. The success rate is about 90% or more, but a small number of women may still get pregnant after taking it. Emergency contraceptive pills have a lot of side effects and are generally not used as a regular contraceptive pill. Some adverse reactions may occur after taking the pill, such as nausea, vomiting, abnormal bleeding, menstrual disorders, etc. Too many times of taking the pill may even cause infertility. It is not recommended to take emergency contraceptive pills more than three times in a year to avoid adverse reactions. Usually try to use condoms or intrauterine device for contraception.