Noticing fluid coming from your nipple can be alarming, particularly if it appears suddenly or without an obvious cause. But nipple discharge is one of the most common breast symptoms women experience, and in the majority of cases it has a completely benign explanation.

At Breast & Surgical Oncology at The Poche Centre, our specialist breast surgeons assess nipple discharge regularly and are expert at identifying whether it is a normal physiological response, a benign breast condition, or something that warrants further investigation. Whatever is causing your discharge, a specialist assessment will give you a clear answer and a plan.

Is Nipple Discharge Normal?

The answer, in many cases, is yes. Nipple discharge is extremely common. Fluid can be expressed from the nipples of the majority of women of reproductive age when the nipple is squeezed or stimulated — this is entirely normal and is referred to as physiological discharge. The breast contains 15 to 20 milk ducts opening onto each nipple, all of which are capable of producing small amounts of fluid as a normal function of glandular tissue.

Physiological discharge has several characteristic features: it is bilateral (both breasts), it comes from multiple duct openings rather than one, it only occurs when the nipple is squeezed or pressed rather than spontaneously, and it is typically cloudy yellow, milky, or green in colour. It is not a sign of disease and requires no treatment — in fact, the most important advice is to stop squeezing the nipple, as doing so stimulates further production and can make physiological discharge appear more persistent than it is.

When Is Nipple Discharge Abnormal?

Nipple discharge moves from physiological to potentially pathological — and therefore requiring specialist assessment — when it has one or more of the following features:

Spontaneous discharge is the most important distinguishing feature. If fluid leaks from the nipple without squeezing, pressing, or stimulating the breast, it should always be assessed regardless of colour, quantity, or which breast is affected. Spontaneous discharge means the pressure within the duct system is sufficient to express fluid on its own — this warrants investigation.

From one breast only (unilateral) — bilateral discharge from both breasts simultaneously is more likely to be physiological or hormonally driven. Discharge from one breast only is more likely to reflect a localised pathological process in the breast tissue.

From a single duct opening — discharge that consistently comes from one specific point on the nipple, rather than multiple openings, suggests a localised abnormality within that particular duct.

Blood-stained, clear, or watery in colour — the colour of nipple discharge provides important diagnostic information. Milky, yellow, or green discharge is almost always benign. Discharge that is bright red, dark brown, or crystal clear (like water) is more concerning and warrants prompt specialist assessment. If the colour is difficult to determine, dabbing a small amount onto a white tissue can help clarify it.

Associated with other symptoms — nipple discharge that occurs alongside a breast lump, skin change, nipple retraction, or nipple skin changes must always be assessed promptly, regardless of whether the discharge itself is spontaneous or blood-stained.

In a man — any nipple discharge in a man is abnormal and requires specialist assessment without delay.

When Should Breast Asymmetry Be Assessed by a Specialist?

For longstanding, stable, minor asymmetry with no associated symptoms, specialist assessment is not medically necessary — though it is always welcome if you want guidance on your options.

You should seek specialist review if:

• The asymmetry has developed or worsened suddenly, rather than being a stable longstanding feature
• There is an associated lump, skin change, nipple change, or breast pain
• One breast has become noticeably larger, smaller, harder, or differently shaped over a relatively short period
• The asymmetry is significant enough to cause physical discomfort — for example, difficulty finding supportive bras, neck or shoulder pain from the imbalance of a larger breast — or is significantly affecting your confidence and quality of life
• You have had breast cancer treatment and are concerned about the appearance of the treated side
• You have been told you have a high-risk breast lesion and asymmetry on mammogram

What Causes Nipple Discharge?

Physiological Discharge

As described above, physiological discharge is a normal response to stimulation of the breast and requires no investigation or treatment. Stopping the habit of checking by squeezing the nipple is all that is needed.

Duct Ectasia

Duct ectasia is one of the most common benign causes of nipple discharge, particularly in women approaching or after menopause. The milk ducts beneath the nipple dilate, their walls become thickened and inflamed, and secretions collect and drain. The discharge is typically bilateral, comes from multiple ducts, and is yellow, green, or dark brown in colour. It is not spontaneous in most cases.

Duct ectasia is benign and does not increase breast cancer risk. Most women require no treatment. If the discharge is persistent, bothersome, or associated with nipple discomfort or retraction, surgical removal of the ducts behind the nipple (total duct excision) can be performed to resolve the problem.

Intraductal Papilloma

An intraductal papilloma is a small, benign wart-like growth arising within a milk duct, most commonly in the ducts just behind the nipple. It is one of the most common causes of pathological nipple discharge, typically producing spontaneous, unilateral, single-duct discharge that is clear or blood-stained.

While papillomas are benign, they require careful specialist assessment for several reasons. Firstly, blood-stained discharge from a single duct always warrants imaging and tissue diagnosis to exclude malignancy. Secondly, intraductal papillomas can be difficult to characterise fully on needle biopsy, and they are generally removed surgically (microdochectomy — excision of the affected duct) both to establish a definitive diagnosis and to treat the symptom. Thirdly, multiple papillomas occurring throughout the duct system (rather than a single solitary lesion) are associated with a modestly elevated future risk of breast cancer and require appropriate surveillance.

Galactorrhoea — Hormonal Milky Discharge

Galactorrhoea is the spontaneous production of milky, breast milk-like discharge unrelated to pregnancy or recent breastfeeding. It is caused by elevated levels of prolactin — the hormone that drives milk production — and is almost always bilateral and from multiple ducts.

Elevated prolactin can be caused by a benign tumour of the pituitary gland called a prolactinoma, by hypothyroidism, or by a range of medications. Drugs known to cause galactorrhoea include antipsychotic and antidepressant medications, some anti-nausea medications (such as metoclopramide), antihypertensives (such as verapamil), and oral contraceptives. Recreational drugs including cocaine can also elevate prolactin levels.

When galactorrhoea is identified, a blood test to measure serum prolactin levels and thyroid function is the first investigation, followed by appropriate imaging of the pituitary gland (MRI) if prolactin is significantly elevated. Treatment is directed at the underlying cause — prolactinoma is typically managed with medication (dopamine agonists such as cabergoline) rather than surgery.

Paget's Disease of the Nipple

Paget's disease of the nipple is a form of breast cancer that affects the skin of the nipple and areola. It typically presents as a persistent, eczema-like rash of the nipple — red, scaly, crusted, or ulcerated — that does not respond to topical treatments. It may be associated with a serosanguineous (bloody or clear-pink) nipple discharge and, in most cases, reflects an underlying breast cancer within the duct system.

Paget's disease is often initially misdiagnosed as eczema or dermatitis and treated with steroid creams, which may provide temporary improvement. Any persistent or recurrent nipple rash — particularly one that has not responded to standard dermatological treatment — should be assessed by a specialist breast surgeon and biopsied to exclude Paget's disease.

Nipple Eczema and Dermatitis

Genuine eczema or dermatitis affecting the nipple skin can produce a weeping, crusty discharge from the surface of the nipple. Unlike Paget's disease, eczema tends to involve both nipples, is part of a broader atopic history, and responds to topical corticosteroid treatment. Any eczematous nipple change that is unilateral, persistent, or unresponsive to appropriate treatment should have Paget's disease excluded before continuing to manage it as benign skin disease.

Breast Cancer

Breast cancer is an uncommon cause of nipple discharge in isolation. Fewer than 5% of women with breast cancer have nipple discharge as a presenting symptom, and in most of those cases, other symptoms such as a lump, skin change, or nipple inversion are also present. However, when blood-stained or clear spontaneous discharge is the presenting complaint, cancer must be excluded through appropriate assessment — even when initial examination and imaging appear normal.

Medications

Beyond those associated with galactorrhoea, several other medications can cause or contribute to nipple discharge through various mechanisms. A thorough medication history is always part of the specialist assessment for nipple discharge.

How Is Nipple Discharge Assessed?

Clinical History

Your specialist will ask detailed questions about your discharge — when it started, whether it is spontaneous or only on expression, which breast and how many duct openings are involved, what colour it is, whether there are any associated symptoms, and your full medication history. This history alone can often narrow the likely cause considerably.

Clinical Examination

A thorough breast examination includes gentle assessment of the nipple to determine which duct opening the discharge is coming from, whether a mass can be felt in the subareolar area, and whether any associated skin or nipple changes are present.

Imaging

Mammography and/or ultrasound are performed to assess the breast and subareolar duct system for any structural abnormality. In some cases, particularly where a duct papilloma is suspected, ultrasound can identify the papilloma directly within the dilated duct.

MRI may be recommended where discharge is persistent, imaging is inconclusive, or where there is clinical concern about malignancy that has not been clarified by other means.

Cytology

Cytology or testing of the discharge fluid is unreliable and is generally not recommended for the investigation of nipple discharge

Biopsy

If imaging identifies a suspicious lesion, a core biopsy under ultrasound guidance will be recommended to obtain a tissue diagnosis. Where no abnormality is identified on imaging but discharge is persistent, spontaneous, and blood-stained, surgical exploration of the duct may be required even in the absence of a visible lesion, as small papillomas and early cancers can be beyond the resolution of standard imaging.

Treatment of Nipple Discharge

Treatment depends entirely on the cause identified through assessment.

Physiological discharge requires no treatment — simply stop squeezing the nipple and the discharge will typically settle within weeks.

Galactorrhoea is treated by addressing the underlying cause — adjusting or changing causative medications in consultation with the prescribing doctor, or treating the underlying hormonal condition (thyroid disease or prolactinoma).

Duct ectasia causing persistent or bothersome discharge can be managed conservatively in mild cases, or surgically with total duct excision if the discharge is significant or associated with nipple discomfort or retraction.

Intraductal papilloma is generally treated surgically. The procedure — a microdochectomy — involves the precise surgical excision of the affected duct, performed under general or local anaesthetic. The duct is identified by inserting a fine probe through the discharging opening, which guides the surgeon to the papilloma during surgery. The excised tissue is sent for pathological analysis to confirm the diagnosis. The procedure typically leaves a small incision around the edge of the areola, which heals with minimal visible scarring.

Where discharge is coming from multiple ducts or the specific duct cannot be identified, a total duct excision — removal of all the duct tissue behind the nipple — may be the more appropriate procedure. This resolves the discharge comprehensively but does affect the ability to breastfeed from that breast, which is a relevant consideration for women who have not yet completed their family.

Blood-stained or persistent spontaneous discharge without an identified cause on imaging is generally also managed surgically, as small papillomas, areas of atypical cells, or early cancers can be below the detection threshold of mammogram and ultrasound. Surgical exploration and excision of the relevant duct provides both a definitive diagnosis and treatment.

Paget's disease requires treatment of the underlying breast cancer, which is managed through our multidisciplinary team with surgery, and systemic and local therapies as appropriate.

When Should I See a Specialist About Nipple Discharge?

See your GP for referral to a specialist breast surgeon if:

• Discharge is spontaneous — occurring without squeezing the nipple
• Discharge is from one breast only
• Discharge appears to come from a single duct opening
• Discharge is blood-stained, clear, or an unusual colour
• You are a man with any nipple discharge
• Discharge is associated with a lump, skin change, or nipple retraction
• Discharge is persistent or has increased despite stopping nipple stimulation
• You have a persistent nipple rash that has not responded to topical treatment

Nipple Discharge Assessment in North Sydney

Our specialist breast surgeons at The Poche Centre in North Sydney assess nipple discharge with the thoroughness and expertise this symptom deserves. We see nipple discharge as a diagnostic challenge that benefits from experienced clinical assessment, the right imaging, and — where needed — precise surgical management.

If you have concerns about nipple discharge, don't dismiss it or wait. A specialist appointment will give you a clear answer.