Engorgement, or breast fullness, is a normal part of lactation. Nearly all women experience engorgement when their milk comes in, usually two to five days after delivery. This feeling of fullness, which may be accompanied by a feeling of heaviness, tenderness, and warmth, is caused by swelling of the breast tissue as blood, lymphatic fluid, and milk collect in the ducts as the process of milk production begins.

This normal breast fullness can develop into engorgement if the baby isn’t nursing often enough or vigorously enough, or if you’re separated from your baby and don’t remove the milk frequently and effectively. When the normal breast fullness is not relieved, fluid builds up and swelling occurs. The breasts become hard, and the skin is taut and shiny. They become extremely tender and painful, and you may run a low-grade fever and become achy. The swelling may extend into the area under the arms, and in very severe cases can cause numbness or tingling of your hands from pressure on your nerves. Because the breast is so full and swollen, the nipple and areola may flatten out, making the tissue difficult for the baby to grasp.

If severe engorgement is not relieved, the milk producing cells at the end of the milk ducts can shrink and may decrease milk production. If the buildup of milk and fluid is not removed, swelling can occur to the point where the milk ducts will actually swell shut, making it much more difficult to get the milk out. Unrelieved engorgement can also lead to plugged ducts and mastitis.

Taking a warm shower or placing warm compresses on your breasts will increase the flow of milk, and decrease the discomfort of engorgement. Pump or hand-express some milk to make your breast soft enough for your baby to latch on easily. Be careful not to pump or express too much milk, since this can prolong engorgement by signaling your body to make more milk.

A cold pack can be applied after breastfeeding if you’re still engorged and uncomfortable. Engorgement is normally not a problem once your baby is nursing well.