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Key Takeaways
- Nipple discharge can be caused by normal hormonal shifts like pregnancy or breastfeeding.
- Discharge from both breasts is likely due to hormonal changes, while one-sided discharge is more concerning.
Breast discharge, influenced by hormonal fluctuations from events like pregnancy, menstrual changes, or even medication use, is usually normal but can vary in color and consistency. Knowing when it signals a more serious issue, such as breast cancer or infection, can provide reassurance and guidance on taking the next steps.
What Do Different Breast Discharge Colors Mean?
Nipple discharge can vary in color and consistency. It is typically thin and clear or white, but it might also appear as the following:
Additionally, it may be:
- Slightly thicker and milky
- Purulent (pus-like) and cloudy
- Very thick, sticky, and cheese-like
If hormones cause nipple discharge, it’s usually milky-white. However, this alone doesn’t confirm the cause since hormonal and non-hormonal causes can overlap.
For example, green breast discharge can occur because of hormonal shifts in pregnant and nursing people, but it can also be a sign of a breast infection.
Whether discharge comes from one or both breasts can offer helpful clues:
Discharge from both breasts is often due to hormonal changes, conditions like thyroid disease, or medications. Discharge from one breast is less likely hormonal and may indicate a disease.
The following may also be used to help differentiate hormonal from non-hormonal causes:
- Does the discharge have an odor?
- Does it occur spontaneously or only when the breast is pressed?
- What other symptoms are occurring? (e.g., a fever can be a sign of a breast infection, while missed periods can be a sign of pregnancy)
How Hormones Could Cause Nipple Discharge
Hormonal causes of breast discharge can include:
- Changes in your menstrual cycle, such as those during the premenopausal and postmenopausal phases
- Pregnancy and lactation
- Galactorrhea
- Medical conditions that affect hormone levels
- Hormonal medications
Menstrual Cycle Changes
Normal fluctuations in estrogen during the menstrual cycle can change breast tissue and lead to nipple discharge. Some experience lumpy, fibrocystic breasts, swelling, and tenderness before their period, along with a bit of nipple discharge, usually milky or green-brown. Discharge can also be due to a decrease in estrogen during menopause.
Pregnancy and Breastfeeding
Colostrum, fluid that comes before breast milk, may leak weeks or months before birth. It typically starts thin and light-yellow, then becomes thicker and milky. This discharge is a normal preparation for childbirth and breastfeeding and is generally not a concern.
Newborns may also have small amounts of clear or milky nipple discharge, sometimes with slight breast swelling or a small lump. This condition stems from leftover pregnancy hormones
Galactorrhea
Galactorrhea is a milky discharge caused by high prolactin levels (hyperprolactinemia). Prolactin is a hormone involved in breast growth and breastfeeding.
Higher-than-usual levels of this hormone can be caused by:
- Acid reflux drugs
- Antidepressants
- Antipsychotics
- Blood pressure drugs
- Dopamine antagonists
- Herbal supplements (e.g., fenugreek, red clover, anise, and fennel)
- Opioids
- Sedatives
Medical Conditions Related to Hormones
Certain health conditions can alter hormone levels. Hypothyroidism (underactive thyroid) and non-cancerous pituitary gland growths can change prolactin levels, causing nipple discharge.
Medications
Medications such as hormonal contraceptives (e.g., birth control pills) and hormone-replacement therapy (HRT) can have a milky nipple discharge as a side effect since they change the levels of hormones (like estrogen) in your body.
Aldactone or Carospir (spironolactone), which is used to treat hormonal acne, can also cause nipple discharge. Selective serotonin reuptake inhibitors (SSRIs) used for depression can cause nipple discharge.
What Else Could Contribute to Discharge?
If you have breast discharge that’s not being caused by something hormonal, your provider may have to look for other possible causes.
Non-hormonal causes of breast discharge can include:
- Blocked milk ducts (ectasia)
- Infections (e.g., mastitis)
- Non-cancerous growths (intraductal papilloma)
- Irritation (e.g., rough clothing or a poor-fitting bra, excess stimulation, trauma)
- Cancer (including Paget’s disease)
Mammary Duct Ectasia
Mammary duct ectasia is the medical term for blocked milk ducts. It’s most common in people who are near menopause (perimenopause) or have gone through menopause. In this condition, the breast ducts widen and become clogged with thick discharge.
Nipple discharge from mammary duct ectasia can be:
- Clear to green, brown, or black
- Very thick and cheese-like
- Accompanied by red, tender nipples
The condition can lead to mastitis. When this happens, the nipples can turn inward (nipple inversion) and may make a person worry they could have breast cancer.
Mammary duct ectasia usually goes away in time, but some cases require surgery. Hot packs can relieve discomfort from the condition.
Bloody discharge later in infancy can also be caused by mammary duct ectasia.
Conditions like mammary duct ectasia and cancer become more common during perimenopause and after menopause. Do not ignore symptoms and ask your provider for testing to rule out these conditions.
Infections
Mastitis is a breast infection that can cause symptoms such as:
- Pus-like yellow-green discharge
- Fever
- Pain
- Breast tenderness
If the nipple discharge is also foul-smelling, it could be coming from an abscess in the nipple or under the areola (the pigmented area around the nipple). An abscess is an area the body “walls off” to keep an infection from spreading. It’s a serious medical problem that needs treatment.
Intraductal Papillomas
Intraductal papillomas are non-cancerous growths usually affecting one duct and are most common before menopause.
The growths often cause a clear or bloody discharge. You may also notice a painless lump on your nipple.
Most of these growths are not a concern, but some may have regions of papillary carcinoma of the breast—a precancerous condition called ductal carcinoma in situ (DCIS).
Breast Cancer
It’s rare, but nipple discharge is sometimes a sign of breast cancer. It can be an early warning sign of breast cancer that is still in the pre-invasive stage. This is more likely in someone over age 40 and/or if:
- The discharge is one-sided and spontaneous (without stimulation)
- The discharge comes from only one duct
- You have other symptoms of breast cancer (e.g., dimpling, retraction, nipple inversion, or a breast mass)
Breast cancer discharge can be bloody, clear, or milky.
Paget’s Disease
Paget’s disease of the breast is an uncommon form of breast cancer. It accounts for less than 3% of cases.
Paget’s disease causes:
- Nipple discharge that’s often bloody
- Nipple tenderness or burning
- Redness, scaling, and/or flaking
It usually takes a biopsy to diagnose Paget’s disease.
Male Breast Discharge
If you’re biologically male and have nipple discharge, see your healthcare provider. It often signals early pre-invasive cancer. Male breast discharge can also result from a small tumor on the pituitary gland, which may go unnoticed until vision changes occur.
Steps to Diagnosing Nipple Discharge
Your provider will do some tests to figure out why you have nipple discharge. The specific tests they do will depend on your age, symptoms, and what is found during a physical exam.
- Blood tests: Commonly include prolactin level and thyroid-stimulating hormone (TSH) tests.
- Brain MRI or CT scan: These scans can check for pituitary microadenoma.
- Cytology: A sample of discharge is collected and examined for cancer cells.
- Ultrasound: This imaging test looks for abnormalities behind the nipple and areola. It can identify papillomas, but a biopsy may also be needed.
- Ductogram: Dye is injected to evaluate breast milk to see if there are any blockages or growths.
- Biopsy: A breast biopsy is done to look at lumps near the nipple. A skin biopsy can help diagnose Paget’s disease.
If breast cancer is a possibility, a breast MRI, ultrasound, biopsy, and a mammogram can be done.
How Is Nipple Discharge Treated?
When hormones are causing nipple discharge, it’s typically part of a normal process in the body. For example, nipple discharge during pregnancy and breastfeeding is expected and does not need to be treated.
If you’re having nipple discharge because of a hormone-related disorder, managing that condition will probably make the symptom better. In the case of low thyroid, for example, Synthroid (levothyroxine) can replace the thyroid hormone you are lacking.
If you’re having nipple discharge as a medication side effect, you could ask your provider about switching to a different medication to see if it helps.
Non-hormonal causes more often require treatment since they usually aren’t part of normal bodily processes.
For example, a bacterial infection is usually treated with antibiotics. An intraductal papilloma that is causing symptoms can be surgically removed.
Avoiding too much breast stimulation, wearing clothes that don’t irritate your breasts, and using warm compresses can help reduce breast discharge. If it is soaking through your clothes, try using nipple pads.