The emergency contraceptive pill can only be used for 72 hours before taking the pill and up to 6 hours after stopping the pill. If you have unprotected sex more than 6 hours after taking the pill, there is no contraceptive effect. The earlier you take the emergency contraceptive pill, the better the effect, if you take it late, there is a high risk of contraceptive failure. The emergency contraceptive pill should not be used more than twice a month and not more than three times a year because it is a highly effective hormone that inhibits the normal secretion of the pituitary ovarian axis, which inhibits ovulation and affects endocrine secretion, so eating too much of it can cause endocrine disorders.