A stye (also spelled sty) is an inflammation of the sebaceous glands at the base of the eyelashes. It is generally caused by a Staphylococcus bacteria infection. Styes are not believed to be infectious. They are particularly common in infants.

The stye may form on either the inside or the outside of the eyelid.

• An external stye will show as a tender, red swelling on the edge of the eyelid and will tend to drain itself quickly.
• An internal stye will also be tender and may show external red swelling. Internal styes often take longer to heal because the abscess cannot drain as easily. These types of styes can also cause blurred vision and irritation.
• Most styes will drain on their own though this may be accelerated with a warm compress. Do not attempt to squeeze the stye, or apply excessive pressure in any way.
• If the condition does not clear up in a few days, consult a medical professional.