The most common cause of breast discomfort is from the effects of hormones on breast tissue from the female menstrual period. Many women experience mild monthly breast pain in conjunction with their periods (menses). For some women, however, the pain can be more severe. This premenstrual breast pain is referred to as cyclic breast discomfort. The exact cause of cyclic breast discomfort has not been determined.
Much less common causes of breast pain include benign growths (tumors) in the breasts (including cysts), breast cancer, and certain medications. It should be noted that breast cancers are often painless and can be detected by manual examination, mammogram, or ultrasound of the breast. Breast pain is called mastodynia, mastalgia, or mammalgia by physicians.