Bleeding one week after taking emergency contraceptive pills is due to the high hormone content in the pills, which affects the uterine lining and causes it to shed, which is a normal phenomenon. Emergency contraceptive pills are a kind of drugs with high content of progesterone, through this high dose of progesterone to inhibit follicular discharge, prevent sperm from passing through the cervix, and prevent the fertilized egg from bedding to play a role. While playing these roles, it will also cause the endometrium to proliferate and shed, which will lead to bleeding for a period of time after taking the pill, this phenomenon is normal. However, it should be noted that emergency contraceptive pills should not be taken for a long period of time, otherwise it may lead to endocrine hormone disruption in the human body, affecting women’s menstrual cycle. The use of emergency contraceptive pills may have adverse reactions such as dizziness, nausea, breast swelling and pain. Therefore, emergency contraceptive pills should be used under the guidance of a doctor to avoid unauthorized use.