Why does a blocked milk duct cause breast pain?

Milk ducts carry milk toward the nipple. If one becomes narrowed, pressure rises behind the narrowed area as milk continues to collect. Nearby tissue can swell and become inflamed, producing soreness, tenderness, or a sensitive firm patch. Pain may be stronger during feeding or when the breast is touched, and it may ease as milk flow improves.

A blocked duct is not the only possible explanation for breast pain. Persistent, severe, or unusual pain should be assessed, especially when it occurs with a lump, fever, skin change, or nipple discharge.

Feed or express in a way that feels comfortable, and avoid trying to empty the breast aggressively. Rest, a supportive but non-tight bra, and a cool pack after feeding can reduce discomfort. Gentle handling is preferable to deep massage. A clinician or lactation professional can review positioning, attachment, and any difficulty with milk removal.

Seek prompt medical advice for fever, chills, spreading redness, marked warmth, pus, rapidly worsening pain, or feeling unwell, as these features can occur with breast inflammation or an abscess. Arrange a check for pain that persists, repeatedly returns, or comes with a new lump or nipple or skin change.

Ask whether the pain fits a blocked duct, whether feeding technique could be contributing, and which comfort measures are suitable for you. Ask how to recognise mastitis, when imaging is appropriate, and what to do if the pain returns.