A stye (sty) is a red, painful lump near the edge of your eyelid that may look like a boil or a pimple. Styes are often filled with pus. A stye usually forms on the outside of your eyelid, but sometimes it can form on the inner part of your eyelid.

In most cases, a stye will begin to disappear on its own in a couple days. In the meantime, you may be able to relieve the pain or discomfort of a stye by applying a warm washcloth to your eyelid.

A stye is a bacterial infection involving one or more of the small glands near the base of your eyelashes. It is similar to a boil or a pimple and is often painful.

Signs and symptoms of a stye include:

A red lump on your eyelid that is similar to a boil or a pimple
Eyelid pain
Eyelid swelling
Tearing
Another condition that causes inflammation of the eyelid is a chalazion. A chalazion occurs when there’s a blockage in one of the small oil glands near the eyelashes. Unlike a stye, a chalazion usually isn’t painful and tends to be most prominent on the inner side of the eyelid. Treatment for both conditions is similar.

When to see a doctor
Most styes are harmless to your eye and won’t affect your ability to see clearly. Try self-care measures first, such as applying a warm washcloth to your closed eyelid for five to 10 minutes several times a day and gently massaging the eyelid. Contact your doctor if:

The stye doesn’t start to improve after 48 hours
Redness and swelling involves the entire eyelid or extends into your cheek or other parts of your face