Breast swelling and pain during menstruation may be related to hormonal changes in the body, or it may be caused by diseases such as breast hyperplasia or breast nodules. 1. Hormonal changes in the body: During menstruation, hormone levels in the female body usually rise, so the breast tissue may become edematous, resulting in breast swelling and pain. However, the swelling and pain will return to normal after menstruation. 2. Breast Hyperplasia: This disease is mainly caused by endocrine hormone imbalance, before menstruation and during menstruation, due to the body’s estrogen will suddenly rise, hormone imbalance may cause the disease. Patients will have symptoms of breast swelling and pain, accompanied by breast lumps and menstrual disorders and other discomforts. 3. Breast nodules: Patients with breast nodules may experience pain and swelling in their breasts during menstruation, and some of them may be able to touch the lumps themselves. In addition, it may also be caused by breast cancer, breast trauma, herpes zoster and other diseases, the specific medical examination can only be clarified.