Nipple has been hard and painful when touched may be physiological normal phenomenon, there may be related to pathological factors such as breast hyperplasia, nipple inflammation, breast tumors and so on. 1. Physiological factors: such as sexual stimulation, hot and cold stimulation caused by nipple hardness and pain, as well as menstruation or breastfeeding women can be due to the influence of hormone levels, and nipple has been hard, a touch of pain symptoms, these are normal physiological phenomena, usually without treatment. 2. Pathological factors (1) Breast hyperplasia: mental factors, long-term use of contraceptives and other factors can cause serious endocrine disorders, further affecting the mammary glands, resulting in breast swelling, nipple hardness and pain. (2) Nipple Inflammation: Most common in lactating primigravid women, the nipple by sucking or saliva impregnation and other factors can be cracked, and then secondary bacterial infection, causing acute nipple inflammation, which can be manifested as unilateral or bilateral nipple redness, swelling, cracking, hardness, pain and other symptoms. (3) Breast tumor: such as breast fibroadenoma, intraductal carcinoma of breast, breast cancer, etc. If they invade to the ducts and nipples, they may show the symptoms of nipple hardness and pain. In addition, breast cancer, breast trauma, breast cysts and other diseases may also show similar symptoms. When the symptoms of hard and painful nipples appear, it is recommended to consult the doctor in time to find out the cause and then treat it actively so as not to delay the condition.