Styes are usually on the surface of your eyelid and easy to see. But they can form deep inside your eyelid. An internal stye (on the underside of your lid) also causes a red, painful bump. But its location prevents a whitehead from showing up on your eyelid. This type can also go away once the infection is gone. Some leave a small fluid-filled cyst that your doctor will have to cut open and drain.

What Causes Styes?

Usually it’s a combination of a clogged oil gland and a certain type of bacteria. Your body is coated with billions of friendly bacteria that live right along with you. Most of the time there’s no problem. But when conditions are right, the bacteria overproduce and create a pimple.

What’s a Chalazion?

If the clogged gland that produces the stye never gets better, scar tissue forms around it. The pain goes away but a bump remains. Doctors call that a chronic chalazion (pronounced cha-LAY-zee-yon).

Styes and chalazia (that’s the plural of chalazion) are usually harmless. They rarely affect your eyeball or eyesight. Rarely they can cause severe infections of the face called cellulitis. They can happen at any age and tend to come back from time to time especially in people who have ongoing eyelid irritation (blepharitis) or a skin condition called rosacea.