Styes are generally not contagious since the bacteria causing them is naturally found on the face; it only becomes a problem when it gets trapped in a clogged hair follicle or gland. However, similar to how bacteria causes a stye for someone else from being in the wrong place, this same thing can occur if the bacteria become trapped in a gland or hair follicle on your eyelid. Because of this, it is important to take precautions to prevent getting an infection from someone else. To be safe, avoid sharing makeup used around the eyes with others, especially mascara or eyeliner.