Styes form when bacteria, almost always Staphylococcus aureus (the common staph bacteria), infect one of the tiny oil glands along your eyelid. These glands normally release a thin layer of oil that keeps your tears from evaporating too quickly. When debris, dead skin, or dried oil blocks a gland’s opening, bacteria that already live on your skin can multiply inside the clogged gland, triggering a small, painful abscess.
What Actually Happens Inside Your Eyelid
Your eyelids contain dozens of oil-producing glands. The ones nestled right at the base of your eyelashes are small and shallow. A stye that forms here, called an external stye, shows up as a visible red bump near the lash line. Deeper inside the eyelid sit larger glands that produce a thicker oil. When one of those gets blocked and infected, the result is an internal stye, a painful swelling that may not be visible from the outside but can make the whole eyelid feel tender and heavy.
In both cases, the sequence is the same: a blockage traps oil, bacteria colonize the stagnant pocket, and your immune system responds with inflammation, redness, and pus. The bump typically grows over a day or two, peaks in tenderness, and then either drains on its own or slowly reabsorbs. Most styes resolve within one to two weeks without treatment beyond warm compresses.
The Most Common Causes
Because the staph bacteria responsible for styes already live on most people’s skin, you don’t need to “catch” anything from someone else. What tips the balance is anything that blocks a gland or introduces extra bacteria to the eyelid margin.
- Touching your eyes with unwashed hands. This is the single most common trigger. Every time you rub your eyes, you push bacteria and debris toward gland openings.
- Old or shared eye makeup. Mascara and liquid eyeliner are safe for roughly three months after opening. Beyond that, bacteria multiply inside the tube. Adding water to dried-out mascara accelerates bacterial growth. Applicator brushes should be washed every seven to ten days.
- Sleeping in contact lenses. Lenses trap bacteria against the surface of the eye and eyelid, giving them more time to colonize gland openings.
- Not removing makeup before bed. Leftover makeup physically blocks gland ducts overnight, creating the exact conditions bacteria need.
Chronic Eyelid Conditions That Raise Your Risk
Some people get styes once and never again. Others deal with them repeatedly. If styes keep coming back, the underlying issue is often a chronic condition affecting the eyelid’s oil glands rather than a single hygiene slip.
Blepharitis, a long-standing inflammation of the eyelid edges, causes redness, thickening, and crusty scales along the lash line. That buildup of debris continuously blocks gland openings, making recurrent styes far more likely. Blepharitis and styes often cycle together: the inflammation causes blockages, the blockages become infected, and the infection worsens the inflammation.
Meibomian gland dysfunction (MGD) is a closely related problem in which the larger, deeper eyelid glands fail to release enough oil, or release oil that’s too thick to flow properly. Most often, the glands simply fill up and can’t drain. Cleveland Clinic identifies recurring styes as a hallmark symptom of MGD. Left untreated, MGD also leads to chronic dry eye, which further irritates the eyelid surface and keeps the cycle going.
Skin Conditions That Affect the Eyes
Rosacea is best known for causing facial redness, but it frequently involves the eyes too. Ocular rosacea triggers chronic eyelid inflammation and meibomian gland dysfunction through an overactive inflammatory response in the skin around the eyes. People with ocular rosacea produce elevated levels of inflammatory compounds in their tear fluid, which destabilizes the tear film and damages gland linings. Recurring styes or chalazions (non-infectious bumps from blocked glands) are a recognized consequence.
Seborrheic dermatitis, the same condition that causes dandruff on the scalp, can also produce flaky, oily skin on the eyelids. That flaking contributes to gland blockages in the same way blepharitis does.
Does Diabetes Play a Role?
People with diabetes face higher rates of eyelid problems overall. In a study of 320 eyes in people with diabetes, 44% showed some degree of meibomian gland dysfunction and nearly 24% had blepharitis. Both conditions are direct precursors to styes. Elevated blood sugar impairs the body’s ability to fight off bacterial infections and can change the composition of the oils your eyelid glands produce, making blockages more likely. If you have diabetes and notice styes returning frequently, it may reflect broader changes in your eyelid health worth addressing.
Can You Catch a Stye From Someone Else?
A stye is generally not contagious. The bacteria that cause it are already present on most people’s skin. That said, it is possible to spread small amounts of bacteria from a stye through direct contact, shared towels, or shared pillowcases. The practical takeaway: wash your hands before and after touching your face while you have a stye, swap out your pillowcase frequently, and don’t share eye makeup or face towels.
How to Lower Your Risk
Most stye prevention comes down to keeping the eyelid margin clean and the oil glands flowing freely.
- Warm compresses. Holding a warm, damp cloth over closed eyes for five to ten minutes loosens thickened oil and clears gland openings. If you’re prone to styes, doing this daily can reduce flare-ups significantly.
- Eyelid hygiene. Gently cleaning along the lash line with diluted baby shampoo or a pre-made eyelid scrub removes the crusty debris that blocks glands.
- Replace eye makeup on schedule. Mascara and liquid liner every three months, pencil liners up to a year. Discard anything that smells off or has changed texture regardless of the timeline.
- Hands off. Avoid rubbing your eyes throughout the day. If you wear contacts, wash your hands thoroughly before inserting or removing them.
- Manage underlying conditions. If you have rosacea, blepharitis, or meibomian gland dysfunction, treating the underlying inflammation reduces stye frequency more effectively than any single hygiene step.