Why do styes appear?

17 July 2025

Styes are a common eyelid inflammation that can be quite uncomfortable. They usually appear as a small red bump, similar to a pimple, typically near the eyelashes. While they are not usually serious, it's important to understand why they occur and how we can prevent them.

A stye (external or internal) is a localized infection, most often caused by the bacteria Staphylococcus aureus. This infection affects the sebaceous glands of the eyelid, specifically:

• External stye: forms at the base of an eyelash, where the glands of Zeiss or Moll are located.

• Internal stye: develops inside the eyelid, in the Meibomian glands.

Both types cause redness, swelling, pain, and sometimes tearing or sensitivity to light.

Most common causes:

1. Poor eyelid hygiene. Touching your eyes with dirty hands, sleeping with eye makeup on, or not properly cleaning contact lenses can allow bacteria to enter.
2. Blepharitis. This is a chronic inflammation of the eyelid margins, which increases the risk of blocked glands and stye formation.
3. Excessive or contaminated makeup use. Sharing makeup, using expired products, or not properly removing eye makeup can promote bacterial growth.
4. Touching or rubbing your eyes frequently. This can transfer bacteria directly to the eyelids, especially if hands are not clean.
5. Stress or low immunity. A weakened immune system can make the body more vulnerable to infections, including styes.
6. Dermatological conditions. Conditions like rosacea or seborrheic dermatitis may increase the likelihood of developing styes.

How can they be prevented?

• Maintain good hygiene of the eyelids and hands.

• Avoid rubbing your eyes.

• Use hypoallergenic makeup and replace it every 3–6 months.

• Do not share eye products.

• Clean contact lenses and their cases regularly.

• Consult a specialist if you have chronic blepharitis.

Although most styes go away within a few days with warm compresses, if the bump grows, the pain increases, or it lasts more than a week, it’s important to see an ophthalmologist. Medical attention is also recommended if styes occur frequently, as this could be a sign of an underlying condition.