Heavy bleeding after taking birth control pills may be due to bleeding caused by the medication, which is a side effect of the medication. However, if the bleeding is heavy, examination is also needed to rule out whether it is caused by abnormal coagulation, submucosal fibroids of the uterus, or cancers of the reproductive tract. Contraceptive pills generally contain progesterone ingredients within the pill, women may experience withdrawal bleeding, irregular vaginal bleeding and menstrual disorders after taking the pill, which is a side effect of the drug. However, it is also possible that the woman has other diseases, such as abnormal coagulation function, due to the use of contraceptive pills induced vaginal bleeding, at the same time, the woman’s coagulation function is abnormal, resulting in heavy bleeding. It is also possible that the patient has reproductive tract tumors such as uterine submucous fibroids, endometrial cancer, etc., leading to heavy vaginal bleeding. Women who take birth control pills with heavy bleeding need to seek timely medical examination to exclude other pathologies and be treated under doctor’s guidance.