Nipple discharge means fluid coming from one or more openings in the nipple. It is common during pregnancy and breastfeeding, but it can also occur at other times. Most causes are not cancer; nevertheless, a new discharge should be assessed because its pattern matters more than colour alone.

Questions that help identify the cause

Your doctor will ask whether the fluid comes out by itself or only when the nipple is squeezed, whether it affects one breast or both, and whether it comes from one duct or several. The colour, duration and relationship to pregnancy, breastfeeding or the menstrual cycle are also useful. Mention any lump, breast pain, fever, new nipple inversion, skin change and all medicines or supplements.

Repeated squeezing can keep a benign discharge going, so avoid checking the nipple again and again before your appointment.

Pregnancy and breastfeeding

Milk or colostrum is the most common explanation during pregnancy, after childbirth and while breastfeeding. A small amount of milk may continue for some time after breastfeeding stops. Pain, redness, warmth, fever or feeling unwell raises concern for mastitis or a breast abscess and needs prompt review.

Benign breast causes

Duct ectasia is an age-related widening and inflammation of the ducts behind the nipple. It may produce thick green, yellow, brown or white discharge and sometimes nipple tenderness or inversion.

An intraductal papilloma is a small benign growth inside a milk duct. It can cause clear or bloodstained discharge, often from one breast and one duct. Cysts, blocked ducts and other non-cancerous changes can also be responsible.

Hormones and medicines

A milky discharge from both breasts outside pregnancy is called galactorrhoea. It may relate to a raised prolactin level, thyroid disease, nipple stimulation or medicines such as some antipsychotics, antidepressants, anti-sickness treatments and hormonal contraceptives. Do not stop prescribed medicine without medical advice; the clinician may arrange blood tests when appropriate.

Can nipple discharge mean breast cancer?

Cancer is an uncommon cause, but it must be considered—especially when discharge is spontaneous, comes from one breast and one duct, or is clear or bloodstained. The level of concern is higher if there is a lump, skin dimpling, eczema-like change of the nipple, new inversion or enlarged lymph nodes. Colour alone cannot confirm or exclude cancer.

What happens at the breast clinic?

Assessment usually includes a clinical breast and lymph-node examination. Ultrasound, mammography or both may be selected according to age and findings. If imaging identifies an abnormality, a needle biopsy may be recommended. Milky bilateral discharge may lead to pregnancy testing, medication review and hormone or thyroid blood tests.

When should you book promptly?

Arrange an appointment for any new nipple discharge that is not clearly related to pregnancy or breastfeeding. Seek earlier review if the discharge is bloody or clear and spontaneous, comes from one breast, or is accompanied by a lump, nipple or skin change. Fever with a hot, red, painful breast requires urgent assessment for infection.

The practical message

Most nipple discharge has a benign explanation, but self-diagnosis from colour is unreliable. A focused history, examination and the right investigations can identify the cause and prevent unnecessary worry.