Ask an Expert: When is nipple discharge a concern?

Q: “I am concerned about some discharge from one of my breasts. If I squeeze the nipple, I get a dark greenish fluid. Sometimes it also occurs spontaneously. I mentioned this during my last physical exam, but my mammogram appeared to be OK. Should I do anything else, or just wait for my next mammogram? If it’s nothing to be concerned about, what is causing it?”

Answer from Heidi Nelson, M.D., M.P.H., medical director of Providence Women and Children’s Program and Providence Women and Children’s Health Research Center

Without examining you myself, I can’t say for sure what is causing your nipple discharge. But I can offer a few reassuring words: Nipple discharge is rarely a sign of cancer.

Unusual nipple discharge is one of the top three breast concerns that women bring up with their doctors (lumps and breast pain are the first two). We see it most often in older women (the chances of having it increase with age) and in women who have had multiple pregnancies.

In addition to your question about green fluid, I’ve recently heard from women asking about sticky grayish-black fluid and about milky yellow fluid. The color and consistency of the fluid can help determine what is causing the discharge.

For example, here are some common conditions that can cause fluid discharge, and the types of discharge they may cause (although there may be variations):
  • Normal breast function: clear, yellow, white, or dark green discharge
  • Pregnancy or breast-feeding: thin and milky, or clear and straw-colored in early pregnancy
  • Hormonal imbalance that’s causing milk production (if not pregnant or postpartum): milky or clear, possibly yellow or green
  • Inflamed duct: yellow, green, brown or black
  • Injury: clear, yellow or bloody
  • Breast infection: pus
  • Fibrocystic breast changes: yellow, green, brown or black
  • Small non-cancerous growth in a duct (papilloma): bloody
  • Breast cancer: bloody
Considering only the color and consistency of the fluid, therefore, your green discharge could be a normal gland secretion that’s unrelated to any kind of medical problem, or it could be the result of a hormonal imbalance, an inflamed duct, or fibrocystic breast changes. Sorting out the actual cause will require more information.

I would tell any woman who experiences unusual breast discharge to make an appointment with her physician, and to be prepared to answer the following questions:
  • How much fluid discharge are you experiencing?
  • Does it happen in one or both breasts?
  • Does it come from one opening in the nipple or multiple openings?
  • Does it happen on its own, or only when the nipple is squeezed?
  • Do you have additional symptoms, such as fever, skin redness, a breast lump, breast pain, headaches, vision changes or anything else?
  • Are you pregnant, or were you recently pregnant?
  • Have you injured your breast recently?
  • What medications do you take?
This information can help a physician either identify the cause of the discharge or determine whether further tests are necessary. Some conditions can be treated; others require no treatment.

You say that you already mentioned this to your physician — that was a smart step. If your physician ordered no further tests or treatment, then whatever is causing your discharge probably doesn’t require treatment. However, since you are still concerned about it and are unsure about what to do next, I encourage you to contact your doctor for follow up. Ask what he or she determined was causing the discharge; what, if anything, you can do to alleviate it; and when you should return for follow up.

If you ever experience nipple discharge that looks like blood or pus, or that is accompanied by other symptoms or breast changes, be sure to get it evaluated promptly. Discharge that is persistent, occurs spontaneously, is present on only one side, or otherwise causes concern also should be evaluated. 

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