Retreat bleeding after taking the emergency contraceptive pill is a vaginal bleeding symptom caused by the side effects of the drug itself. As long as the bleeding is not too much and is not accompanied by other discomfort, no treatment can be given and the bleeding usually improves or disappears in 2-5 days. Emergency contraceptive pills can cause fluctuations in hormone levels in the body, increasing estrogen and progesterone levels, and later when estrogen levels drop, it can cause some of the endometrium to shed, resulting in withdrawal bleeding. Emergency contraceptive pills may affect the menstrual cycle and the endocrine function of the ovaries, so it is not recommended to take emergency contraceptive pills frequently.