A sty is a painful red bump on the edge of the eyelid that is caused by an infection of oil glands in the eyelid. The bacterium staphylococcus is commonly responsible for most of these infections. The following are some of the causes of a sty:

• Touching your eyes with unwashed hands
• Inserting contact lenses without thoroughly disinfecting them or washing your hands first
• Leaving on eye makeup overnight
• Using old or expired cosmetics
• Having long-term blepharitis, dandruff, rosacea, diabetes, or high levels of bad cholesterol

Most styes are harmless to the eye and wont affect your ability to see clearly. In most cases, a sty will begin to disappear on its own in a couple of 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. However, if the sty doesnt start to improve after 48 hours, or if redness and swelling involve the entire eyelid or extend into your cheek or other parts of your face, you should contact your doctor. If your vision seems to be affected, you should also see a doctor.