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

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

Symptoms Causes Risk factors Prevention

Signs and symptoms of a sty include:

  • A red lump on your eyelid that is similar to a boil or a pimple
  • Eyelid pain
  • Eyelid swelling
  • Tearing
  • Crusting around the eyelids

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 at the margin of the eyelid, just behind the eyelashes. The gland can become infected with bacteria, which may also cause a red, swollen eyelid. Unlike a sty, a chalazion tends to be most prominent on the inner side of the eyelid. Treatment for both conditions is similar.

When to see a doctor

Most sties 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 10 to 15 minutes several times a day. Contact your doctor if:

  • The sty doesn't start to improve after 48 hours
  • Redness and swelling extend beyond your eyelid and involve your cheek or other parts of your face

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