Nipple discharge refers to any fluid that excretes out of the nipple of the breast. Nipple discharge in women who are not pregnant or breastfeeding may not be abnormal, but it’s wise to have any unexpected nipple discharge evaluated by a doctor. On the other hand, nipple discharge in men under any circumstances could be a problem and needs further evaluation.

One or both breasts may produce a nipple discharge when you squeeze your nipples or breasts. Any nipple discharge may look milky, or it may be clear, yellow, green, brown or bloody. The consistency of nipple discharge can vary — it may be thick and sticky or thin and watery. Nipple discharge that occurs spontaneously and/or is brown or bloody in color, is more concerning and should be evaluated by a healthcare professional.

Nipple discharge is a normal part of breast function during pregnancy or breastfeeding. It also may be associated with menstrual hormone changes and fibrocystic changes. The milky discharge after breastfeeding will normally affect 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. It appears spontaneously and involves a single duct. Although the bloody discharge may resolve on its own, this situation requires evaluation with an ultrasound of the area behind the nipple and areola. If the ultrasound shows a lesion within a milk duct, you may need a biopsy to confirm that it’s a papilloma or to exclude cancer.

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
  • The discharge is spontaneous and persistent
  • The discharge affects only a single duct

Possible causes of nipple discharge include:

  • Abscesses
  • Birth control pills/oral contraceptives
  • Breast cancer
  • Ductal carcinoma in situ (DCIS)
  • Endocrine disorders
  • Excessive breast stimulation
  • Fibrocystic disease of the breast
  • Injury/trauma to the breast
  • Intraductal papilloma
  • Mammary duct ectasia
  • Mastitis
  • Medication usage
  • Menstrual cycle/hormonal changes
  • Paget’s disease of the breast
  • Pregnancy and breastfeeding
  • Prolactinoma

Nipple discharge is rarely a sign of breast cancer, but it might be a sign of an underlying condition that requires treatment. If you are experiencing bloody nipple discharge, spontaneous nipple discharge, or continuing nipple discharge that has not resolved, see your healthcare provider for further evaluation. They will perform a physical examination, possibly culture the discharge fluid and will likely order additional testing like a mammogram and/or ultrasound. Following imaging, they might refer you to a breast surgeon for evaluation and/or biopsy.

In the meantime, avoid nipple stimulation, including frequent checks for discharge, because stimulation can cause continued discharge.