Understanding Nipple Discharge: Causes and When to Seek Medical Attention

Nipple discharge is a common occurrence during the reproductive years, even if you are not pregnant or breastfeeding. It is estimated that over 80% of women will experience nipple discharge at some stage in their lives. Given that each breast contains around 20 milk ducts, it is not uncommon for fluid to seep from them. Discharge of milk from the nipple during pregnancy or breastfeeding is entirely normal.

While nipple discharge is usually not a cause for concern, it is crucial to keep in mind that, in rare instances, it may indicate a more serious issue, such as breast cancer. If you observe anything out of the ordinary, it is wise to consult a healthcare provider.

Types of nipple discharge

To understand the different types of discharge, the healthcare provider may ask you several questions regarding the colour and nature of the discharge. Here are some common types of nipple discharges:

• Clear or watery discharge from nipple: A clear or watery discharge from both nipples is generally not a cause for concern; however, if it comes from only one breast, it could be a sign of breast cancer.
• Bloody discharge: A blood discharge from the nipples can occur due to papilloma, a noncancerous tumour. This condition may lead to breast irritation, and in rare instances, a bloody discharge could also be a sign of breast cancer.
• Milky or white discharge: Nipple discharge is a common issue for women, often occurring after they have recently stopped breastfeeding. It is also not unusual for women approaching menopause to experience milky discharge or white discharge from nipples due to hormonal changes.
• Green nipple discharge: A green-coloured discharge from the nipple may occur due to a cyst located beneath the areola or nipple.

Is nipple discharge normal?  

Nipple discharge may be normal if it:

• Is clear, yellow, white, green or brown
• Originates from both the breast
• Originates if you squeeze nipples
• Originates from milk ducts
• However, nipple discharge is not normal if it:
• Is bloody, which is typically a cause for concern
• Originates from only one breast
• Originates on their own without touching or squeezing the nipples
• Is accompanied by symptoms such as breast pain, redness, swelling or changes in the appearance of the nipple

Causes

Nipple discharge is occasionally an indication of a serious issue, such as breast cancer. Harmless causes of nipple discharge can include:

• Changes or imbalances of hormones (during menstruation or menopause)
• Pregnancy or breastfeeding
• Medications like birth control pills and some antidepressants
• Noncancerous cyst
• Stimulation of the nipple or friction from cloth
• Sexual arousal
• Injury to your breast
• Stress

Healthcare providers view nipple discharge as abnormal when it happens spontaneously (without breast stimulation), is bloody or occurs in just one breast. Various health conditions can lead to abnormal nipple discharge, including:

• Papilloma (a noncancerous tumour in the breast)
• Breast infection or abscess
• Mammary duct ectasia
• Severe underactive thyroid gland (hypothyroidism)
• Pituitary gland tumour
• Fibrocystic breast condition (normal lumpiness in the breast)
• Cancerous breast tumour (though rare)
• Paget’s disease of the breast

It is common for newborns to experience some nipple discharge. This occurs due to hormones from their birth parent during pregnancy. Typically, it resolves on its own within a few weeks. Additionally, individuals who breastfeed might notice a milk-like fluid leaking after they stop breastfeeding.

It is always a good idea to consult with a healthcare provider to rule out any serious conditions that might be causing nipple discharge.

Is nipple discharge a sign of breast cancer?

Nipple discharge can indeed be associated with breast cancer, particularly in cases of ductal carcinoma in situ (DCIS), which is an early stage of breast cancer that originates in the milk ducts. It may also occur with Paget’s disease of the breast, a rare form of breast cancer that affects the nipple.

If breast cancer is present, the discharge is likely to come from just one breast. You might also notice a lump in that breast. However, it is important to note that discharge is not commonly caused by cancer. Studies show that the likelihood of nipple discharge being linked to malignant cancer ranges from about 9% to 21%.

Regardless, it is wise to have any new breast discharge evaluated by a healthcare professional.

Diagnosis

Healthcare providers diagnose nipple discharge through a physical examination and by discussing your medical history. The tests they use to determine the cause of the discharge include:

• Imaging: Your healthcare provider might recommend tests such as a mammogram (breast X-ray), ultrasound and magnetic resonance imaging (MRI) to assist in identifying the cause.
• Biopsy: If a physical exam or imaging tests reveal an abnormality, your healthcare provider may take a sample of breast tissue for additional testing.
• Hormone blood test: Your healthcare provider will take a blood sample to check your thyroid and prolactin levels.
• Ductogram: It involves your healthcare provider injecting a contrast dye into your milk ducts, followed by a mammogram to examine the ducts.

Treatment

Treatment for nipple discharge varies based on the underlying cause. Possible approaches include:

• Adjusting or discontinuing a medication
• Surgically removing a lump or cyst
• Extracting a milk duct
• Prescribing antibiotics for breast infections
• Addressing the condition leading to the discharge

If there is no clear reason for your nipple discharge, treatment may not be necessary. Simply avoiding any squeezing of your nipples could be sufficient. Your healthcare provider might suggest a follow-up exam or mammogram to ensure everything is okay.

When to seek medical attention?

If you experience any of the following symptoms, it is crucial to consult a healthcare professional promptly:

• Pain or tenderness in the breast
• Redness or swelling of the breast
• Fever or chills
• Thick, yellowish discharge that does not improve with antibiotics
• Bloody discharge
• A lump in the breast
• Alterations in the breast’s size or shape  
• Skin changes like dimpling or puckering

Conclusion

Nipple discharge is generally not a major concern, but it is good to have it evaluated. Factors such as the colour of the discharge, how often it occurs and whether it comes from one or both breasts can assist a healthcare provider in identifying the cause. A healthcare provider will conduct a breast examination and may suggest imaging tests if deemed necessary. While it is uncommon for nipple discharge to indicate breast cancer, it may point to another underlying medical condition. In most instances, nipple discharge in women is linked to hormonal changes, a blocked milk duct or a benign lump or tumour. Conversely, nipple discharge in men is typically considered abnormal.