May also be called: Sty; Hordeolum Externum

A stye is a red, painful bump on the eyelid caused by a backed-up oil gland.

More to Know

Eyelids have lots of oil glands. They can't be seen without a microscope, but these glands produce the liquid-like substance that helps lubricate the front of the eyes along with tears.

Sometimes, these glands can get clogged with old oil, dead skin cells, and old skin bacteria. When this happens, liquid builds up in the clogged gland and can't get out, creating a stye.

A stye can appear on either the upper or lower eyelid, as well as the inside or the outside of the eyelid, near the edge of the eyelid where the eyelashes are.

Keep in Mind

A stye is usually a minor problem that can be treated at home, simply by placing a warm washcloth over the eye a few times a day. The stye should begin to improve over a few days but if it doesn't or it becomes worse, call your doctor.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.