Itchy nipples during menstruation may be related to hormone level changes, nipple inflammation, nipple eczema, tumors and other reasons. 1. Changes in hormone levels: When a woman is menstruating, the level of estrogen and progesterone in her body changes, which may cause a certain amount of stimulation to the breasts, resulting in itchy nipples. 2. Nipple inflammation: women usually do not pay attention to personal hygiene, bacteria and other pathogenic microorganisms invade the nipple tissue induced nipple inflammation, resulting in itchy nipples during menstruation. 3. Nipple eczema: this disease is common among breastfeeding women. The occurrence of this disease may be related to mental stress, genetic factors, contact with soap and other irritating substances, which can lead to itchy nipples during menstruation. 4. Tumor: with special type of breast cancer such as mammary eczema-like cancer, malignant tissues will invade the nipple, manifesting as itching of unilateral nipple, areola and its surrounding skin, with red patchy eczema-like appearance, and the surface is mostly oozing and crusting or keratinized and desquamated, and ulcers can be formed in serious cases. Itchy nipples may also be due to nipple trauma, allergies, etc. It is recommended that women go to the hospital to improve the blood routine, breast ultrasound, molybdenum target and other related examinations, to clarify the cause of itchy nipples.