By Mayo Clinic Staff

Nipple discharge refers to any fluid that seeps out of the nipple of the breast.

Nipple discharge in women who are not pregnant or breast-feeding may not be abnormal, but it's wise to have any unexpected nipple discharge evaluated by a doctor. Nipple discharge in men under any circumstances could be a problem and needs further evaluation.

One or both breasts may produce a nipple discharge, either spontaneously or when you squeeze your nipples or breasts. A nipple discharge may look milky, or it may be clear, yellow, green, brown or bloody. Nonmilk discharge comes out of your nipple through the same nipple openings that carry milk. The consistency of nipple discharge can vary — it may be thick and sticky or thin and watery.

Nipple discharge is a normal part of breast function during pregnancy or breast-feeding. It also may be associated with menstrual hormone changes and fibrocystic changes. The milky discharge after breast-feeding 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 a cancer.

Nipple discharge is rarely a sign of breast cancer. But it might be a sign of an underlying condition that requires treatment.

If you're still having menstrual periods and your nipple discharge doesn't resolve on its own after your next menstrual cycle, make an appointment with your doctor to have it evaluated. However, if you've completed menopause and you're experiencing a spontaneous nipple discharge that involves one breast and a single duct, see your doctor right away for further evaluation.

In the meantime, take care to avoid nipple stimulation — including frequent checks for discharge — because stimulation actually makes the discharge continue.

Dec. 10, 2016