If you don’t change your underwear in time, most of the nipple pain is caused by the squeezing of the breast tissue, or it may be caused by diseases, such as mastitis and nipple inflammation, etc. The nipple pain is caused by the squeezing of the breast tissue. 1. Breast tissue is squeezed: wear underwear to choose the right size, if the replacement of underwear is not timely, the size is not appropriate, will lead to long-term compression of breast tissue caused by blood stagnation, resulting in nipple pain and other phenomena. 2. Disease: Some women do not change their underwear in time, which can lead to an increase in the possibility of breast infection, such as mastitis, nipple inflammation and so on, thus causing nipple pain. Some women before and after menstruation due to the body’s estrogen secretion is strong, will lead to breast swelling and pain and other symptoms caused by nipple pain, after menstruation pain symptoms will gradually ease. At the same time, more sensitive skin, allergic to underwear materials, underwear replacement is not timely may also appear nipple pain. It is recommended that when nipple pain occurs for unknown reasons, it is recommended to consult a regular hospital to clarify the cause under the guidance of a doctor, so as to avoid delaying the condition.