Breast swelling and pain during menstruation is a relatively common menstrual manifestation. The reasons for the appearance of this symptom. First, it is a normal physiological reaction, related to the change of hormone level in the body during menstruation, which leads to the acceleration of blood circulation in the breast area and congestion and edema of breast tissue. After the menstrual period is over, the symptoms will disappear. Second, some women may suffer from breast diseases such as breast enlargement, breast fibroids, breast cysts, etc., causing symptoms of breast swelling and pain during menstruation. In this case, there will be different degrees of breast swelling and pain during the non-menstrual period, only that this symptom will be further aggravated during the menstrual period and before the onset of menstruation. Ultrasound examination of the breast can be performed to clarify the diagnosis and treatment.