Breast pain after menstruation is an abnormal symptom, patients are advised to go to the regular hospital for examination first, which may be the symptom of certain diseases, such as breast hyperplasia, breast cysts, mastitis and so on. 1. Mammary hyperplasia: breast pain may occur after menstruation, which may be accompanied by breast nodules or lumps, and in a few cases, nipple discharge. 2. Breast cysts: usually have no obvious symptoms, mainly manifested as a lump in the breast; when the cyst expands acutely, it may lead to sudden and severe confined pain. 3. Mastitis: the main symptom is localized pain, with obvious tenderness and redness of the skin, and even systemic reactions such as chills and high fever. There may be other factors such as breast trauma, breast cancer, etc., but this symptom alone is not enough to diagnose the disease. It is recommended that the patient should consult a doctor in time to clarify the cause of the disease and give targeted treatment.