There are many reasons for nipple swelling and pain, the more common one is pregnancy in women of childbearing age. After pregnancy, the level of chorionic gonadotropin in the body gradually increases, and when the hormone level changes, the blood circulation in the breast area increases, and blood vessel congestion causes nipple enlargement, edema and other manifestations, coupled with the high sensitivity of the nipple due to external stimulation will cause local pain symptoms. In the pre-menstrual period due to hormone level changes will lead to breast pain, after menstruation the symptoms will gradually ease or disappear, the pain is mainly localized tingling. When the localized pain gradually aggravates, you can go to the hospital for examination in time, because malignant breast cancer and mastitis are very similar. Malignant breast cancer is very similar to mastitis. Malignant breast tumors grow faster, and when they invade the nipple area, they will cause local redness, swelling, heat and pain.