Emergency contraceptive pills are effective as long as they are taken orally within 72 hours. The principle of the emergency contraceptive pill is to inhibit the secretion of mucus from the cervical canal, thus inhibiting the union of sperm and egg and achieving the effect of contraception. The emergency contraceptive pill is about 80% effective and has a high chance of success, as long as it is taken orally within 72 hours. If you experience a delay in your period after taking the pill, it is recommended that you take an early pregnancy test to rule out the possibility of conception. Emergency contraceptives can also have adverse effects, causing withdrawal bleeding and disruption of the menstrual cycle. The performance may be different for each person, so it is recommended to observe to see if there is any abnormal performance.