Should I be concerned about nipple discharge? 

Nipple discharge refers to fluid that leaks out of the nipple when you are not breastfeeding. This fluid can vary in colour from clear or milky to yellow, green, brown, grey or bloody. It may leak out on its own or when you squeeze your nipples or breasts. 

In most cases, nipple discharge in women is not serious; however, in 2–15% of cases, it can be a sign of breast cancer, which is why it is important to have any new nipple discharge investigated by a doctor. 

Nipple discharge in men is not normal and should always be investigated by a doctor. 

To understand nipple discharge, it helps to first understand the anatomy of the breast. 

Breast anatomy

In women, each breast contains 15–20 sections called lobes, arranged like the petals of a flower. Each lobe is further divided into lobules. These lobules can make milk and are connected to tiny tubes called mammary ducts. The mammary ducts run towards the nipple where they can then release the milk. 

Nipple discharge occurs when fluid flows out of these ducts when you are not breastfeeding. 

Is nipple discharge normal?

Around one in five women will experience nipple discharge that isn’t caused by any serious underlying health condition. This is called benign nipple discharge and is not serious. It is caused by hormonal changes and usually affects both breasts. This type of nipple discharge is not continuous. 

Conditions that cause nipple discharge

In some cases, nipple discharge is caused by an underlying health condition. 

Galactorrhea

This refers to milky discharge produced from both breasts without being pregnant and when not breastfeeding or having finished breastfeeding for at least a year. Although galactorrhea usually occurs in women, in rare cases, it can occur in men, usually due to male hypogonadism. 

In women, galactorrhea occurs when levels of the hormone prolactin are too high (hyperprolactinemia). Prolactin is produced by a pea-sized gland at the base of your brain called the pituitary gland and stimulates your breasts to produce milk. 

Consequently, galactorrhea can be caused by a non-cancerous tumour on your pituitary gland. It can also be caused by medications that stimulate prolactin production as a side effect, such as certain antidepressants, antipsychotics, high blood pressure medications and sedatives. 

Galactorrhea is usually diagnosed with a blood test to measure serum prolactin levels and an MRI scan of the brain to check for any abnormalities of the pituitary gland. 

Mammary duct ectasia 

This refers to widening of one or more mammary ducts. The ducts become enlarged and inflamed and can fill with a white or greenish fluid that may leak from your nipples. It can also cause your breasts to feel tender and if a duct becomes blocked, you may develop periductal mastitis. 

Mammary duct ectasia usually affects women aged 45–55 years (ie women going through perimenopause), but it can also occur later in life after menopause. 

Intraductal papilloma

This refers to a non-cancerous growth in a mammary duct. An intraductal papilloma can cause continuous nipple discharge from your breast without you squeezing your breast. It is possible to develop multiple papillomas — this is called papillomatosis and occurs in around one in 10 women who develop an intraductal papilloma. 

Papillomas very rarely develop into breast cancer but if you have a papilloma, it will need to be removed and examined in a laboratory to confirm that it is non-cancerous. 

Breast cancer

In around 2–15% of cases of nipple discharge, it is due to breast cancer. Nipple discharge caused by breast cancer occurs in one breast. Discharge is usually continuous and can be clear or bloody in colour. 

Nipple discharge caused by breast cancer may be accompanied by other symptoms of breast cancer, such as a new lump in your breast, dimpling of your breast skin, nipple pain, pulling of your nipple, and swelling and/or redness of part of your breast. However, in some cases, nipple discharge may be the only sign.

Treating nipple discharge

Nipple discharge that isn’t caused by an underlying health condition usually settles down on its own without any treatment. However, if it persists and becomes a bother, for example, due to leakage onto your clothes, your doctor may suggest surgically removing your mammary ducts (total duct excision).

Treatment for nipple discharge that is caused by an underlying health condition will be specific to the particular condition. 

Galactorrhea can be treated by taking medication, such as bromocriptine or cabergoline, to reduce your prolactin levels and/or surgery to remove the pituitary gland tumour. If it is caused by medication, your doctor may be able to recommend alternative medications. 

Mammary duct ectasia can get better on its own without treatment. You can apply warm compresses to help ease any discomfort. However, depending on the severity of your symptoms, your doctor may recommend a course of antibiotics. If your symptoms persist, your doctor may recommend surgery to remove the affected duct (microductectomy). 

Intraductal papilloma is also treated with surgery to remove the affected duct (microductectomy) — this is usually a day case procedure, so you can return home on the same day as your operation. 

Treatment of breast cancer will depend on the type and stage of your breast cancer. It may involve surgery, chemotherapy, radiotherapy, hormonal therapy, immunotherapy and targeted cancer drugs.