There may be several reasons for nipple swelling and hardening: 1, friction, if the underwear material is rough or underwear is too large can lead to nipple has been rubbing underwear, nipple stimulation may cause nipple swelling and hardening, need to replace the soft, suitable underwear. 2, allergy, may be due to the breast skin allergy to the underwear material leads to the nipple has been stimulated, and thus the nipple swelling and hardening, you can take oral xantamine anti-allergy, and at the same time, replace the underwear. 3, Trauma, can also lead to breast inflammation, nipple has been stimulated, can be given a towel hot compress, oral pulse blood Kang blood stasis. 4, mastitis, breast hyperplasia caused by inflammation of the breast and nipple swelling hard, can be taken orally Sivipu pain, Cefaclor capsule anti-inflammatory, supplemented with massage techniques. 5, breast hyperplasia, hormone level disorders, endocrine disorders can lead to breast hyperplasia, may cause nipple swelling hard, and may cause the nipple swelling hard, and the nipple can be used as an alternative to the nipple, and the nipple is not as hard as it should be. Normally, you can give a towel hot compress with massage techniques, pay more attention to rest.