Milk ducts in the breast may become blocked during breast-feeding when the breasts are full and not emptied regularly or thoroughly. Blocked milk ducts cause a lump that is occasionally tender and can become infected (mastitis).

Blocked milk ducts may be treated by:

• Breast-feeding more often and in different positions, which helps drain milk from all parts of the breast.
• Breast-feeding from the affected breast first, to move milk through the breast faster.
• Applying moist heat to the area just before breast-feeding and hand-expressing or pumping a small amount of milk.
• Massaging the area, always working toward the nipple, to increase the flow of milk before and during breast-feeding.