Acne also seems to trigger styes in some adolescents.
Styes and chalazia are infections and inflammations of the tiny oil glands on the eyelids.
Styes come to a head in about three days when they open and drain.
Staphylococcus aureus bacteria are thought to be responsible for most styes.
Rubbing the eyes, especially when the sty is oozing pus, can spread the infection along the eyelid and cause other styes.