There are many reasons why nipples suddenly become larger, the specific analysis is as follows: 1, puberty development, in the period of breast development breasts and nipples will become larger, belongs to the normal physiological performance, do not worry, give children a good psychological construction can. 2, pregnancy and lactation, in the progesterone and lactogen stimulation breast, nipple enlargement, secretion of milk to prepare for breastfeeding, need to keep the nipple clean, clean. 3, nipple The first thing you can do is to apply ice packs and then hot packs 48 hours later, and apply erythromycin ointment, which will heal in a few days. 4, nipple allergy, wearing a poor quality corset, using a bad breast cream leads to nipple allergy, nipple pain, swelling and itching, you need to change good quality household products, while taking oral antihistamine medication.