Styes are an infection of the eyelash follicle caused by bacteria.
A sore similar to a pimple or a boil forms at the edge of the eyelid. More than 1 stye can occur at one time because the bacteria may spread to another follicle. Styes usually develop within a day or 2 and eventually fill with pus then drain spontaneously. A lump that forms on the eyelid may be a stye or a chalazion . Wash hands thoroughly after touching or treating boils , acne , or skin infections and before touching the skin around the eye.