A stye on your eye is caused by a bacterial infection, most commonly by Staphylococcus aureus. This infection blocks an oil gland or an eyelash follicle at the edge of the eyelid, leading to a red, swollen, and painful bump that resembles a pimple

. Specifically:

• An external stye results from infection of the glands of Zeis or Moll at the eyelash base.
• An internal stye occurs when the meibomian glands inside the eyelid become infected

Factors that can contribute to developing a stye include:

• Touching or rubbing your eyes with unclean hands, which transfers bacteria to the eyelid

• Poor eyelid hygiene or leaving eye makeup on overnight, which can promote bacterial growth

• Having underlying conditions like blepharitis (eyelid inflammation), rosacea, or seborrheic dermatitis, which increase susceptibility

• Other risk factors include diabetes and skin conditions that affect the eyelids

Styes are similar to acne pimples and usually develop over a few days. They may drain and heal on their own but can sometimes become larger or recur if underlying issues persist

. Preventive measures focus on good hygiene, such as washing hands before touching the eyes, cleaning eyelids regularly, removing eye makeup before sleep, and avoiding sharing towels or cosmetics

. In summary, a stye is caused by a bacterial infection that blocks an eyelid gland or follicle, often triggered by poor hygiene, eye rubbing, or underlying eyelid conditions