reasons why nipples are hard and sore?
['Exercise and sports. Share on Pinterest Nipple pain is seldom a symptom of a serious condition. ... ', 'Allergies and sensitivities. ... ', 'Sexual activity. ... ', 'Breast-feeding. ... ', 'Thrush. ... ', 'Pregnancy. ... ', 'Menstrual cycle. ... ', 'Perimenopause and menopause.']