Painful bumps on nipples may be caused by folliculitis, breast eczema, breast cancer and other diseases. 1. Folliculitis: this disease is mainly caused by Staphylococcus aureus infection, considering the existence of damage to the nipple follicles, which is related to factors such as skin trauma, wearing tight clothes and excessive sweating. Typical symptoms are the presence of pimples, pain, itching and other symptoms at the lesions, which can be manifested as sore nipples with bumps. 2. Breast eczema: the cause of this disease is not clear, but it may be related to mental stress, heredity, breast moisture and sweating or contact with allergens. The skin lesions mostly appear in the nipple, areola and other places, localized pimples, pain and other symptoms, so the sore nipples with bumps may be caused by breast eczema. 3. Breast cancer: research shows that the occurrence of this disease is related to heredity, abnormal estradiol and estrone levels, over-nutrition, obesity, radiation therapy and other reasons. If it is nipple eczema-like cancer, patients will have unilateral nipple pain, itching and other symptoms, and ulcers will be formed when it is serious, so some patients have the situation of nipple with lumps pain. At the same time, intraductal papilloma of the breast, dilated ducts of the breast, etc. may also be manifested as lumps in the nipple, which need to be carefully identified. It is recommended that patients with sore nipples go to the hospital, complete the relevant examinations, clarify the cause of the disease, and standardize the treatment under the guidance of the doctor.