Quick answer
Colour matters less than pattern. Discharge that is spontaneous, from one duct on one side, and bloodstained or clear needs prompt assessment. Discharge that only appears when squeezed, comes from several ducts on both sides, and is milky, green or brown is usually physiological.
Key takeaways
- Three features carry most of the weight: is it spontaneous, is it one side only, and is it bloodstained or clear.
- Milky, green, grey or brown discharge from multiple ducts on both breasts, appearing only on squeezing, is usually benign duct-related change.
- Bloodstained or clear watery discharge from a single duct on one side is the pattern that warrants urgent assessment, whatever your age.
- NICE recommends considering a suspected cancer pathway referral for people aged 50 and over with discharge, retraction or other change affecting one nipple only.
- Milky discharge from both breasts when you are neither pregnant nor breastfeeding can point to a hormonal or medication cause and is worth investigating on its own terms.
- Repeatedly squeezing the nipple to check keeps the discharge going. Stop checking and see someone instead.
Nipple discharge is one of the symptoms patients most often try to interpret from a chart of colours before coming in. It is a reasonable instinct, and it is only partly useful. Colour narrows the field, but three other features do far more work: whether the discharge appears on its own, whether it is confined to one side, and whether it comes from a single duct opening or several.
Get those three right and you can place almost any discharge into the reassuring group or the needs-looking-at group. Rely on colour alone and you will misclassify in both directions.
Which nipple discharge is normal and which is not?
The clinical distinction is between physiological discharge, which is a normal duct doing normal things, and pathological discharge, which is a signal from a single abnormal duct.
Physiological discharge is typically provoked rather than spontaneous — it appears when you squeeze and not otherwise. It usually involves both breasts, comes from several duct openings, and can be milky, yellow, green, grey or brown. It is common, it is not dangerous, and the more you check it the longer it persists, because expressing the duct is itself the stimulus that keeps it producing.
Pathological discharge is spontaneous: it marks your bra or your nightclothes without you doing anything. It comes from one duct opening, on one side, and it is usually bloodstained or clear and watery. That combination is the one that needs imaging and examination rather than reassurance.
What does each nipple discharge colour usually mean?
With the caveat that colour is the weakest of the four signals, here is what each tends to indicate.
| Colour and character | Usual pattern | What it commonly means | What to do |
|---|---|---|---|
| Bloodstained, pink or rust-coloured | Spontaneous, one duct, one side | Most often an intraductal papilloma, a small benign growth inside a duct. A minority of cases are due to DCIS or an invasive cancer. | Arrange assessment promptly, whatever your age |
| Clear and watery | Spontaneous, one duct, one side | Same differential as bloodstained discharge. Clear serous discharge is treated with the same level of concern. | Arrange assessment promptly |
| Milky, both sides | Spontaneous or provoked, multiple ducts | Pregnancy or breastfeeding. Outside those, raised prolactin from medication or, less often, a pituitary cause. | See your GP for a prolactin level and a medication review |
| Green, grey or thick and sticky | Provoked, multiple ducts, often both sides | Duct ectasia — widened ducts, common around the menopause. Benign. | Mention it at a routine appointment; urgent assessment is not usually needed |
| Yellow or brown | Provoked, multiple ducts | Long-standing duct secretions. Usually benign. | Mention it; assess if it becomes spontaneous or one-sided |
| Yellow-green pus with pain and redness | One side, with a tender lump | Infection or a breast abscess, sometimes related to smoking or a duct that has become blocked. | Seek same-day medical review; this needs antibiotics or drainage |
| Any discharge with a lump, skin or nipple change | Any | The additional finding raises the priority regardless of the discharge itself. | Arrange assessment promptly |
“The two questions I ask before anything else are: did it come on its own, and is it one side? If the answers are yes and yes, the colour barely changes what I do next.”
Mr Debashis Ghosh, Consultant Breast and Oncoplastic Surgeon
If your discharge is spontaneous, one-sided or bloodstained, do not wait to see whether it settles. Our same-day one-stop breast clinic brings consultation, examination, imaging and biopsy where it is needed into one visit, and our breast pain and nipple discharge service covers the full pathway. We also see our clinic for Mayfair patients.
Nipple discharge: frequently asked questions
Is bloodstained nipple discharge always cancer?
No. The most common cause is an intraductal papilloma, a small benign growth inside a duct. But a minority of cases are caused by DCIS or an invasive cancer, and there is no way to tell the difference by looking, which is why bloodstained discharge is always assessed with imaging and examination.
What does it mean if I have milky discharge but I am not pregnant?
Milky discharge from both breasts outside pregnancy and breastfeeding is called galactorrhoea, and it usually reflects a raised prolactin level. Common causes are medications, including some antidepressants, antipsychotics and anti-sickness drugs, and less commonly a benign pituitary condition. It is worth a blood test and a medication review with your GP.
Does the colour tell you whether it is serious?
Only partly. Bloodstained and clear watery discharge sit at the concerning end, and green, grey or brown discharge from both sides sits at the reassuring end. But whether the discharge is spontaneous, one-sided and from a single duct tells you considerably more than the colour does.
Should I keep checking by squeezing my nipple?
No. Expressing the duct is itself the stimulus that keeps discharge going, so repeated checking prolongs a symptom that would otherwise settle, and it can make the picture harder to interpret at assessment. Note what you have observed and stop squeezing.
When does NICE say nipple discharge should be referred?
NICE NG12 recommends considering a suspected cancer pathway referral, meaning an appointment within two weeks, for people aged 50 and over with discharge, retraction or other concerning change affecting one nipple only. Below 50, one-sided spontaneous discharge is still assessed, and the presence of blood or a lump raises the priority.
What tests are used to investigate nipple discharge?
Clinical examination first, then imaging chosen for your age and breast density, usually mammography, ultrasound or both. If imaging identifies a lesion, a needle biopsy samples it. Testing the fluid itself is of limited value, so it is not routinely relied on.
Can nipple discharge be treated?
It depends on the cause. Physiological discharge needs no treatment and settles when you stop expressing it. Duct ectasia is usually managed conservatively. An intraductal papilloma or a persistent single-duct discharge may be treated by removing the affected duct, a small operation called a microdochectomy.
Related reading: At What Age Should You Start Private Mammograms?
Spontaneous or one-sided discharge? Get it assessed
Consultant-led examination and imaging, with a biopsy and results in the same visit where the pathway allows.
Sources
- NICE NG12 — Suspected cancer: recognition and referral. referral thresholds including one-sided nipple change from age 50
- Cancer Research UK — Breast cancer symptoms. includes fluid leaking from the nipple among the symptoms to report
- NHS — Nipple discharge. when to see a GP and what happens next
- NHS — Breast pain. context for discharge occurring alongside pain
This article provides general information and does not replace personalised medical advice, diagnosis or treatment. If you have a breast symptom that concerns you, arrange an assessment.
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