A stye comes from a bacterial infection in one of the tiny oil or sweat glands along your eyelid. The bacterium responsible is almost always Staphylococcus aureus, one of the most common bacteria living on human skin. It normally sits on your eyelids, eyelashes, and nasal passages without causing problems, but when it gets trapped inside a blocked gland, it triggers an acute abscess: the red, painful bump you recognize as a stye.
How a Stye Forms
Your eyelids contain dozens of small glands that produce oil and moisture to keep your eyes lubricated. When one of these glands gets clogged, bacteria that already live on your skin can multiply inside the blocked opening and cause an infection. The result is a localized pocket of pus, similar to a pimple or boil.
There are two types, depending on which gland is affected. An external stye, the more common kind, develops at the base of an eyelash where smaller oil and sweat glands sit. An internal stye forms deeper in the eyelid, inside a larger oil-producing gland called a meibomian gland. Internal styes tend to be more painful because of their location, but both types follow the same basic pattern of blockage, bacterial overgrowth, and inflammation.
Why Some People Get Them More Often
Styes are extremely common, but certain conditions make them more likely to recur. Blepharitis, a chronic inflammation of the eyelid margins, is one of the biggest contributors. When the edges of your eyelids stay irritated and flaky, the gland openings are more prone to clogging. People with rosacea, which can affect the eyes as well as the face, also tend to have oilier, more inflamed eyelid margins that create a hospitable environment for repeated infections.
Everyday habits play a role too. Sleeping in eye makeup, using expired cosmetics, or not fully removing mascara and eyeliner can block gland openings. Contact lens wearers face a higher risk if they skip proper hand washing before handling their lenses, don’t clean the lenses thoroughly, or store them in old solution. Each of these shortcuts creates an opportunity for bacteria to transfer from your fingers or contaminated products into the delicate gland openings along your lash line.
What a Stye Feels Like
The hallmark of a stye is a very painful red bump along the edge of the eyelid, right at the base of the eyelashes. It often swells quickly, and in some cases the entire eyelid puffs up. You may notice a small white or yellowish pus spot at the center of the bump.
Other common symptoms include:
- A scratchy, gritty feeling, as if something is stuck in your eye
- Sensitivity to light
- Crustiness along the eyelid margin
- Excess tearing from the affected eye
Stye vs. Chalazion
People often confuse styes with chalazia, and the two can look similar at first glance. The key difference is pain. A stye is acutely painful from the start and sits right at the eyelid’s edge. A chalazion is a firm bump that develops farther back on the eyelid, caused by a clogged oil gland that becomes inflamed but not actively infected. Chalazia are rarely tender and don’t usually make the whole eyelid swell. Sometimes an untreated stye evolves into a chalazion once the acute infection fades but the blocked gland remains.
How Long a Stye Lasts
Most styes resolve on their own within one to two weeks. The main home treatment is a warm, wet compress applied to the closed eyelid for 5 to 10 minutes, repeated 3 to 6 times a day. The heat helps soften the blocked material inside the gland and encourages it to drain naturally. Resist the urge to squeeze or pop a stye, which can spread the infection into surrounding tissue.
If pain and swelling haven’t started improving after about 48 hours of consistent warm compresses, or if they get noticeably worse after the first two to three days, it’s worth having an eye doctor take a look. In rare cases, a stye can progress to a deeper skin infection around the eye called periorbital cellulitis. Warning signs of this include fever, increasing pain, swelling that spreads beyond the eyelid into the surrounding eye socket, vision changes, or the eye beginning to bulge forward. These symptoms need immediate medical attention.
Reducing Your Risk
Because styes start with bacteria getting into a blocked gland, prevention comes down to keeping your eyelids clean and minimizing bacterial transfer. Wash your hands before touching your face or eyes. Remove all eye makeup before bed, and replace mascara and eyeliner every few months rather than using them until they run out. If you wear contact lenses, clean and store them exactly as directed, and throw away any lenses you were wearing around the time a stye appeared to avoid reintroduction of bacteria.
Washing your pillowcases, towels, and washcloths regularly also helps, since Staphylococcus aureus survives on fabric surfaces. If you have blepharitis or oily, flaky eyelids, a daily eyelid hygiene routine using a warm washcloth or lid scrub can keep gland openings clear and reduce the chances of another stye forming.