If you haven’t heard of a bleb, you may have heard of a milk or nipple blister. They are a tiny, painful sac filled with milk on the tip of the nipple or areola. It will look as if the skin has grown over the duct opening and stopped the milk from coming out. Click here to read how to treat and prevent blebs. Lactation, Nursing, Breastfeeding, Tips and Tricks for Breastfeeding, Painful Breastfeeding, Clogged Milk Ducts