The causes of nipple pain include physiological factors, pathological factors and bad habits in daily life. 1. Physiological factors: the level of estrogen in a woman’s body changes with the menstrual cycle or pregnancy. When a woman’s endocrine disorders, the hormone secretion in her body is out of balance, which may stimulate the sensory nerve endings distributed in the nipple, and the phenomenon of nipple pain occurs. 2. Pathological factors: such as cracked nipples, nipple inflammation, nipple eczema, Paget’s disease, etc., can stimulate the distribution of the nipple’s nociceptive nerve, thus causing nipple pain. 3. Bad habits: such as wearing poorly ventilated and ill-fitting underwear, improper breast cleansing or breastfeeding, as well as excessive mental stress or frequent use of contraceptives, etc., which may irritate the skin on the surface of the nipple or affect the normal secretion of estrogen. If there is only mild nipple pain and no other discomfort, you can first observe at home and improve your lifestyle. If the nipple pain is more serious or the nipple is localized with redness, swelling, erosion, overflow, etc., you should go to the hospital in time, get a clear diagnosis and then treat under the guidance of the doctor to avoid delaying the condition.