Nipple discharge means any fluid that comes out of a breast nipple.

Nipple discharge during pregnancy and breast-feeding is typical. At other times, it may not be cause for worry. But it's good to have a healthcare professional examine your breasts if the nipple discharge is a new symptom. Men who ever have nipple discharge should have a medical exam.

Discharge can come from one or both breasts nipples. It might happen from squeezing the nipples or breasts. Or it might happen on its own, called spontaneous. The discharge comes through one or more of the ducts that carry milk.

The fluid might look milky, clear, yellow, green, brown, gray or bloody. It can be thin and sticky or thin and watery.

Nipple discharge is a typical part of how the breast works during pregnancy or breast-feeding. It also can be linked to menstrual hormone changes and common changes in breast tissue, called fibrocystic breast. The milky discharge after breast-feeding most often affects both breasts. It can continue for up to one year or more after giving birth or stopping nursing.

A papilloma is a noncancerous, also called benign, tumor in a milk duct. A papilloma can be linked to bloody discharge. The discharge linked with a papilloma often happens spontaneously and involves a single duct.

The bloody discharge may clear up on its own. But your healthcare professional is likely to want a diagnostic mammogram and a breast ultrasound to see what's causing the discharge.

You also may need a biopsy to confirm that it's a papilloma or to rule out a cancer. If the biopsy shows a papilloma, a member of your healthcare team will refer you to a surgeon to talk about treatment options.

Often, a harmless condition causes nipple discharge. However, the discharge might mean breast cancer, especially if:

• You have a lump in your breast.
• The discharge comes from only one breast.
• The discharge is bloody or clear.
• The discharge happens on its own and is ongoing.
• You can see that the discharge is coming from a single duct.

Possible causes of nipple discharge include:

• Abscess.
• Birth control pills.
• Breast cancer
• Breast infection.
• Ductal carcinoma in situ (DCIS)
• Endocrine conditions.
• Fibrocystic breasts
• Galactorrhea
• Hypothyroidism (underactive thyroid)
• Injury or trauma to the breast.
• Intraductal papilloma.
• Mammary duct ectasia
• Medicines.
• Menstrual cycle hormone changes.
• Paget's disease of the breast
• Periductal mastitis.
• Pregnancy and breast-feeding.
• Prolactinoma
• Too much handling of the breast or pressure on the breast.

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

If you still have menstrual periods and your nipple discharge doesn't clear up on its own after your next menstrual cycle, make an appointment with your healthcare professional.

If you're past menopause and you have nipple discharge that happens on its own, is clear or bloody and from a single duct in one breast only, see your healthcare professional right away.

In the meantime, don't massage your nipples or handle your breasts, even to check for discharge. Handling your nipples or friction from clothing can cause ongoing discharge.