What causes nipple discharge?

Discharge can be milk-like, clear, yellow, green, or blood-stained. It may come from one or both breasts and appear only after squeezing or without touch. Breastfeeding, recent pregnancy, and raised prolactin can cause milk-like discharge. Some medicines and thyroid or pituitary problems can also alter prolactin.

Duct ectasia can cause sticky or coloured discharge as a milk duct widens and thickens. An intraductal papilloma may cause discharge from a single duct. Infection can bring pain, warmth, redness, or fever. Nipple discharge is a presentation of breast cancer in some people, including Paget disease of the breast, so a new or unusual pattern should be assessed.

Note the colour, amount, side, whether it appears spontaneously, and any lump, pain, skin or nipple change. Avoid repeatedly squeezing the nipple, as stimulation can maintain discharge. Arrange a clinical assessment for new, persistent, one-sided, spontaneous, or blood-stained discharge. The clinician may examine the breast and decide whether imaging or blood tests are useful.

Seek prompt medical review for blood-stained or clear discharge from one breast, a new lump, nipple inversion, a crusted or eczematous nipple, or skin dimpling. Get urgent care if discharge occurs with fever, rapidly spreading redness, severe pain, or feeling very unwell, as infection may need immediate treatment.

What does the colour and pattern suggest? Could a medicine or prolactin level be contributing? Do I need breast imaging? Which nipple or skin changes should prompt faster review?