There are many reasons why nipples can hurt to touch: 1. Nipple injuries, nipples are squeezed, hit or cut resulting in red, swollen, painful or even bleeding nipples. If there is no wound on the surface, you can apply a cold compress first, then a hot compress after 48 hours, spray Yunnan Baiyao if necessary, if there is bleeding you can press to stop the bleeding to prevent infection. 2, nipple allergy, if you come into contact with allergic substances that cause allergy to the nipple, there will be nipple pain, swelling and itching. The symptoms will disappear after the menstruation. 4. Breast cancer, which is not painful in the early stage but invades the nerves in the late stage, will cause breast pain and nipple retraction and swelling, and needs immediate treatment.