A stye is a painful red bump on the edge of the eyelid that may look like a boil or a pimple. It is caused by a bacterial infection in the oil-producing glands in the eyelid. The bacterium staphylococcus is commonly responsible for most of these infections. The infection occurs when bacteria from the skin, which normally exist harmlessly on the skin of the eye, get trapped along with dead skin cells on the edge of the eyelid. Touching mucus from the nose and then touching the eye can also cause the spread of staphylococcal to the eyelid. Certain things can increase the risk of developing styes, such as touching the eyes without washing hands, not disinfecting contact lenses, using old cosmetics, and having blepharitis, which is chronic redness on the edge of the eyelid. Reoccurring styes may indicate that eyelids need to be cleaned more often.