One of the tiny oil glands on your baby's eyelid is probably infected. It occurs when bacteria such as Staphylococcus aureus infects the gland at the base of an eyelash. The infection produces a tender red pus-filled bump or boil. You may also notice some yellow or white discharge from the bump and her eyelid may get a little crusty.
Most sties respond well to a simple home remedy.
Although he will probably wiggle and resist you, try to hold the compress there for five minutes at a time, and repeat three or four times a day. The process can go more smoothly if you sing to your baby while you apply the compress or do it when he's asleep or distracted by a feedings. The heat will draw the pus to the front of the sty, and it will break open and drain. Once the sty drains, wash your baby's eyelid with a clean cloth or cotton ball and some warm water to keep the infected pus from spreading. Any remaining swelling should disappear within a week.