Nipple discharge is a typical part of breast function during pregnancy or breast-feeding. It may also be associated with menstrual hormone changes and fibrocystic changes. The milky discharge after breast-feeding usually affects both breasts and can continue for up to two or three years after stopping nursing.

A papilloma is a noncancerous (benign) tumor that can be associated with bloody discharge. The discharge associated with a papilloma often occurs spontaneously and involves a single duct. Although the bloody discharge may resolve on its own, your doctor will likely recommend a diagnostic mammogram and a breast ultrasound to see what's causing the discharge. You may also need a biopsy to confirm that it's a papilloma or to exclude a cancer. If the biopsy confirms a papilloma, your doctor will refer you to a surgeon to discuss treatment options.

Often, nipple discharge stems from a benign condition. However, breast cancer is a possibility, especially if:

  • You have a lump in your breast
  • Only one breast is affected
  • The discharge contains blood or is clear
  • The discharge is spontaneous and persistent
  • The discharge affects only a single duct

Possible causes of nipple discharge include:

  1. Abscess
  2. Birth control pills
  3. Breast cancer
  4. Breast infection
  5. Ductal carcinoma in situ (DCIS)
  6. Endocrine disorders
  7. Excessive breast stimulation
  8. Fibrocystic breasts (lumpy or rope-like breast tissue)
  9. Galactorrhea
  10. Injury or trauma to the breast
  11. Intraductal papilloma (a benign, wartlike growth in a milk duct)
  12. Mammary duct ectasia
  13. Medication use
  14. Menstrual cycle hormone changes
  15. Paget's disease of the breast
  16. Periductal mastitis
  17. Pregnancy and breast-feeding
  18. Prolactinoma

Causes shown here are commonly associated with this symptom. Work with your doctor or other health care professional for an accurate diagnosis.

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Dec. 04, 2021