What Causes Nipple Discharge?

Nancy is a 27-year-young woman who came to see me with a complaint of on and off nipple discharge over the past four weeks.  Nipple discharge, or what we nerdy doctors call galactorrhea, actually happens in about half of all women of child-bearing age, believe it or not.  And most of the time, it’s not anything serious to worry about.  But it’s still important to see your doctor just to be sure it’s not caused by a more serious health problem.

What Causes Nipple Discharge?

There are many potential causes of nipple discharge, so in order to find out what’s going on with Nancy, I asked her to describe her symptoms in more detail.  She said that her discharge is white and milky, it is coming from both breasts, and she is often able to express the discharge by squeezing her breasts.

Signs Your Nipple Discharge Isn’t Serious

Thankfully, Nancy’s description tends to be more consistent with benign causes.  Signs your nipple discharge isn’t serious include discharge that is:

• from both breasts

• easily produced by manipulation of the breasts

• white, clear, or milky

More Serious Signs of Nipple Discharge

On the other hand, signs that your breast discharge might be more serious include discharge that:

• occurs only in one breast

• is spontaneous

• is bloody or brown

• is associated with a breast mass

Causes of Nipple Discharge

Whether your nipple discharge seems more serious or not, however, it’s still very important to see your doctor for an evaluation.  To further figure out why Nancy is experiencing nipple discharge, I must go through a mental list of all the possibilities that can cause a nipple discharge in women like Nancy.  So, I dig a little deeper into the mystery while Nancy is still in my office.  Here is that mental list that runs through my brain as a doctor:

1. Breast Cancer: Of course breast cancer is the worst possible cause of nipple discharge, but likely one of the least common as well. When I examined Nancy, she thankfully did not have any breast lumps or masses, and her breast exam was completely normal. Based on her age (27), benign description of the discharge, and normal breast exam, breast cancer is quite an unlikely cause of her nipple discharge.
2. Trauma and Breast Manipulation: Sometimes trauma to the chest, like a steering wheel injury in a car accident, can injure the milk ducts and produce nipple discharge. Just as common a cause, continued repeated breast manipulation, whether it’s by your partner or yourself, can also induce nipple discharge. Nancy denied any injuries or breast manipulation of any kind.
3. Lactation and Postpartum: Women who have just given birth–whether or not they are breast feeding–will produce milk. That is one of the most common causes of benign nipple discharge. But Nancy’s last pregnancy was over four years ago.
4. Hormonal Abnormalities: Very rarely, thyroid disorders can cause a hormonal imbalance that causes nipple discharge. A simple blood test showed that Nancy’s thyroid was normal. However, if it wasn’t normal and hormones were to blame, the nipple discharge would typically resolve once the thyroid was treated.
5. Pituitary Tumor: Another less common cause of nipple discharge is a pituitary tumor. The pituitary is a gland in the brain that causes the release of a hormone called prolactin. This prolactin goes to the breasts and tells the ducts to produce milk when women are lactating. When a tumor of the pituitary arises, it overproduces prolactin and may cause women to produce milk at inappropriate times. A simple blood test for prolactin levels ruled this out for Nancy.
6. Pregnancy: Pregnancy itself increases prolactin levels and can cause benign nipple discharge. Elevated estrogen levels in pregnancy are also thought to increase prolactin levels. Nancy was relieved to hear that her pregnancy test was negative…phew!
7. Stress: Believe it or not, there are some studies that show elevated stress levels, whether they are psychologic or physiologic, can cause elevated prolactin. Nancy has normal everyday stressors, but nothing out of the ordinary, new, or significant going on in her life.
8. Medications: Medications aren’t always without side effects. And there are some medications that can elevate prolactin levels and cause nipple discharge too. I reviewed Nancy’s medication list with her, and she denied taking oral contraceptives (although they very rarely cause galactorrhea), anti-psychotic medications like Risperdal, metoclopramide for anti-nausea, and no blood pressure medications like verapamil or methyldopa.

However, she did report recently being prescribed a cough syrup with codeine in it for a chronic cough that she’s had since the beginning of springtime, when her allergies typically kick in.  She’s been miserable with this cough, which has kept her up at nights, and has been taking this cough syrup with codeine, that is not supposed to be used chronically, every single night.  Opiates, such as codeine or morphine, can be a cause of nipple discharge in women.  We have finally solved our nipple leak mystery!

One more thing I should mention. I knew from the beginning that Nancy’s discharge wasn’t bloody, but if it had been, I would have had to rule out another cause of nipple discharge–intraductal papilloma, which is a benign non-cancerous tumor that grows into the milk ducts. And as I said earlier, it’s a good idea to visit your doctor whenever you experience this symptom.

How to Treat Nipple Discharge

I told Nancy to stop the cough syrup immediately, and instead prescribed her a medicated nasal spray that is the main treatment for allergic coughs.  When she came back to see me in two weeks, her cough was gone and her nipple discharge resolved. So as you can see, once your doctor can get to the root of what’s causing your nipple discharge, it can be relatively easy to treat.

Don’t forget to like the House Call Doctor Facebook page, where you can read my health-related posts and links, and where you can ask me your medical questions!

Please note that all content here is strictly for informational purposes only.  This content does not substitute any medical advice, and does not replace any medical judgment or reasoning by your own personal health provider.  Please always seek a licensed physician in your area regarding all health related questions and issues.

Breast image from Shutterstock