Why does a blocked milk duct cause painful breastfeeding?

When milk does not move freely through a duct, the nearby breast tissue can become swollen and tender. Feeding or expressing milk then presses on an already sensitive area. You may feel a sore, firm patch or a tender area that changes after a feed. A blocked duct can occur when feeds are missed, milk is removed less effectively, or pressure is placed on the breast. Pain during feeding can also have other causes, so the symptom alone does not identify its cause.

Continue breastfeeding if you can, beginning on the comfortable side if that makes let-down easier, and avoid forceful massage or deep pressure over the tender area. Check that your baby is well attached and vary feeding positions so different parts of the breast drain. Rest, drink to thirst, and use a cool pack after feeding for swelling. A clinician or lactation specialist can assess attachment and suggest suitable pain relief.

Contact a healthcare professional promptly if you develop fever, chills, worsening redness, marked swelling, pus, or feel generally unwell. Seek assessment if the pain or firm area is not improving, keeps returning, or makes feeding difficult. These changes can signal inflammation or infection that needs examination.

Ask whether the tender area fits a blocked duct, how to improve milk transfer, and which pain-relief options are compatible with breastfeeding. You can also ask what changes should prompt an urgent review.