Styes are caused by bacterial infection of the tiny oil glands along your eyelid margin. The culprit is almost always Staphylococcus aureus, a common bacterium that lives on skin and lashes. When one of these glands gets blocked, its oily secretions stagnate, creating a warm, sealed environment where bacteria multiply and trigger the painful, red bump you recognize as a stye.
How the Infection Starts
Your eyelids contain dozens of small glands that produce oils to keep tears from evaporating too quickly. The glands most often involved in styes are called the glands of Zeis, and there are one to two of them attached to every single eyelash. These glands secrete oil directly into the hair follicle. When debris, dead skin cells, or thickened oil plugs the opening of one of these glands, the secretion backs up. Bacteria that normally live harmlessly on your eyelashes then colonize the trapped oil, and infection sets in.
This is the external stye, the type most people get. It forms right at the lash line and points outward. A less common version, the internal stye, develops deeper in the eyelid when one of the larger oil glands embedded in the eyelid’s structural plate becomes infected. Internal styes tend to be more painful because they press against the eye itself, but the underlying process is the same: blocked gland, trapped secretion, bacterial overgrowth.
Why Some People Get Styes Repeatedly
A single stye can happen to anyone. Recurring styes point to an underlying condition that keeps your eyelid glands inflamed or clogged. The most common is blepharitis, a chronic low-grade inflammation of the eyelid margins. With blepharitis, the oil your glands produce becomes thicker and waxier than normal, making blockages more likely. Many people with blepharitis don’t realize they have it because the symptoms (mild flaking, occasional grittiness) are easy to ignore.
Ocular rosacea is another frequent driver. People with this condition experience recurrent eye and eyelid infections, including styes, along with redness, dryness, and a gritty or burning sensation. If you get styes alongside facial flushing or persistent redness across your cheeks and nose, rosacea may be the connection.
Other factors that raise your risk include hormonal changes that alter oil composition, chronic dry eye, and any condition that weakens your immune response.
Everyday Habits That Contribute
Beyond medical conditions, several daily behaviors introduce bacteria to your eyelids or promote gland blockage.
- Old makeup: Eyelashes naturally carry bacteria, so the moment a mascara wand or eyeliner brush touches your lashes, it picks up those organisms. Over time, bacteria build up inside the cosmetics container, increasing your infection risk with every use. Experts recommend replacing eye cosmetics every three to four months. Storing makeup in hot environments (above 85°F) also weakens preservatives and accelerates bacterial growth.
- Touching your eyes: Rubbing your eyes or applying contacts with unwashed hands transfers bacteria directly to the eyelid margin. Contact lens wearers face additional risk if they skip proper lens cleaning or wear lenses longer than recommended.
- Sleeping in makeup: Leaving eye makeup on overnight gives bacteria hours of uninterrupted contact with your lash follicles while also physically blocking gland openings.
- Sharing cosmetics: Borrowing someone else’s mascara or eyeliner introduces unfamiliar bacterial strains your eyelid defenses may not handle as easily.
What a Stye Feels Like and How Long It Lasts
A stye typically begins as a tender, slightly swollen spot near the lash line. Over a day or two it develops into a visible red bump, often with a yellowish or white center. The eyelid may swell enough to make blinking uncomfortable, and your eye might water more than usual. Some people describe it as feeling like a splinter just under the skin.
Most styes resolve on their own within one to two weeks. The bump usually pops and releases pus after a few days, which brings rapid relief. Warm compresses speed this process along. Placing a clean, warm, damp cloth over the closed eyelid for five to ten minutes several times a day helps soften the blocked oil and encourages the stye to drain naturally. When you start using warm compresses, the bump may temporarily look bigger before it opens and clears.
Styes vs. Chalazia and Other Eyelid Lumps
Not every bump on the eyelid is a stye. A chalazion forms from the same type of gland blockage but without active infection. It tends to develop more slowly, feels firm rather than tender, and sits deeper in the lid. Chalazia are generally painless and can linger for weeks or months if left alone.
A more serious concern, though rare, is sebaceous carcinoma, a skin cancer that can develop on the eyelid. It typically appears as a slowly growing, firm, painless lump, sometimes with a yellowish tint. Unlike a stye, it does not resolve on its own. Key warning signs include a growth that bleeds, a sore that heals and then reappears, or thickening of the eyelid along the lash line. Any new eyelid growth that persists for more than two weeks without improvement deserves a closer look from a doctor.
Preventing Styes Before They Start
Good eyelid hygiene is the single most effective way to prevent styes, especially if you’re prone to them. A simple daily routine can make a significant difference. Start by gently cleansing the lid area with a specialty eyelid wipe, a gentle face wash, or a makeup remover formulated for the eyes. This clears away the debris and excess oil that lead to blockages.
Hypochlorous acid sprays have become a popular second step. Originally used for conditions like blepharitis and dry eye, these solutions help reduce bacteria and inflammation on the eyelid surface. One to two sprays on closed lids after cleansing can keep bacterial populations in check. Look for formulas free of alcohol, oil, sulfates, and added fragrance.
Finally, a daily warm compress helps keep your oil glands flowing freely. A heated eye mask that delivers moist, uniform warmth for 8 to 12 minutes is ideal, because that’s roughly how long it takes to liquefy thickened oil inside the glands. Even once a day, at whatever time is convenient, makes a measurable difference for people who deal with recurrent blockages.
When a Stye Becomes Dangerous
Most styes are a nuisance, not a threat. In rare cases, the infection can spread beyond the stye into the surrounding eyelid tissue, causing a condition called preseptal cellulitis. Signs include significant swelling and redness spreading across the entire eyelid, warmth to the touch, and fever. If the infection pushes deeper into the eye socket, it becomes orbital cellulitis, which is a medical emergency. Symptoms at that stage include severe eye pain, vision changes, the eye visibly bulging forward, and high fever. This progression is uncommon but requires immediate emergency care.