Nipple discharge

Nipple discharge is fluid released from the nipple when a woman is not breastfeeding (and, less commonly, in men). Its meaning depends heavily on its character and pattern. A milky, white or clear discharge from both breasts, often expressed rather than spontaneous, is called galactorrhoea and is usually hormonal rather than a breast disease. The commonest driver is a high level of the hormone prolactin, which normally causes milk production. Prolactin can be raised by a benign pituitary tumour (a prolactinoma), an underactive thyroid, pregnancy and breastfeeding, nipple stimulation, and — very commonly — a range of medications, including some for mood, psychiatric conditions, nausea and blood pressure. In these cases the discharge often comes with menstrual changes or, in a larger pituitary tumour, headaches or visual problems. A quite different and more concerning pattern is a discharge from a single breast and single duct, especially if it is bloody or blood-stained, occurs on its own without squeezing, or comes with a lump or skin change — this points to a local breast problem (usually benign, such as a small duct growth, but occasionally more serious) and needs prompt evaluation. So the key questions are: is it from one breast or both, is it milky or bloody, and is there a lump — which together guide whether the cause is hormonal or a breast issue to investigate.

• High prolactin (galactorrhoea) — milky discharge from both breasts; from a pituitary tumour (prolactinoma), medications, an underactive thyroid, or nipple stimulation.
• Medications — many drugs raise prolactin (some antidepressants, antipsychotics, anti-nausea and blood-pressure drugs).
• Underactive thyroid (hypothyroidism) — can raise prolactin.
• Pregnancy and breastfeeding — normal.
• A single-duct or bloody discharge from one breast — a local breast cause (often a benign duct growth, occasionally more serious); needs assessment.
• Breast infection — a pus-like discharge with pain and redness.

The approach depends on the pattern. For a milky discharge from both breasts (galactorrhoea), tests centre on the hormones: prolactin (the key test), TSH for an underactive thyroid, and a pregnancy test, along with a medication review, and, if prolactin is genuinely high, a pituitary MRI. For a discharge from a single breast or duct, especially if bloody or with a lump, the priority is not blood tests but breast assessment — clinical examination and imaging (ultrasound and/or mammography) to identify the local cause. Mediora.AI can surface a high-prolactin or thyroid pattern from your results that explains galactorrhoea, but nipple discharge — particularly if from one breast, bloody, or with a lump — needs in-person breast assessment by your doctor.