After taking the emergency contraceptive pill, you may experience withdrawal bleeding within 3-7 days of stopping the pill, which is counted as a period. The next period will be recalculated according to the first day of withdrawal bleeding, for example, if withdrawal bleeding occurs on December 1, the next period will usually come around January 1. If there is no withdrawal bleeding, the period will follow the normal cycle, for example, if the last period was on December 1, the next period will be around January 1. Depending on the individual’s menstrual cycle, there may be early or late fluctuations. One of the side effects of oral emergency contraceptive pills is that it can cause abnormal menstruation, mainly in the form of delayed menstruation. If your period is delayed for more than 7 days, you need to go to the hospital for further examination to rule out the possibility of pregnancy, because the success rate of contraception with the correct oral emergency contraceptive pill is only about 85%. It is not recommended to use the emergency contraceptive pill, as a regular form of contraception. Any delay in menstruation and abnormal bleeding should alert you to the occurrence of pregnancy and ectopic pregnancy.