A stye forms when bacteria, almost always Staphylococcus aureus, infect one of the tiny oil glands along your eyelid margin. The process is straightforward: an oil gland gets blocked, secretions build up behind the blockage, and bacteria that normally live on your skin colonize the stagnant oil. The result is a red, painful bump that looks like a small pimple right at the edge of your eyelid. Styes are extremely common, though most people want to know what causes them so they can avoid one, not trigger one.
How a Stye Actually Forms
Your eyelids contain dozens of small glands that produce an oily substance designed to keep your tears from evaporating too quickly. Some of these glands open at the base of your eyelashes, while larger ones sit deeper inside the eyelid itself. When one of these glands becomes plugged, the oil thickens and stagnates. Bacteria that already live on your eyelid skin move into the blocked gland and multiply, triggering an immune response. That response is the swelling, redness, and tenderness you recognize as a stye.
The blockage itself can happen for several reasons. Dead skin cells, dried oil, or debris from makeup can physically seal a gland opening. Chronic inflammation along the eyelid margin (a condition called blepharitis) causes the lining of these ducts to thicken and narrow over time, making blockages more likely. Once the gland is sealed off, infection typically follows within a day or two.
External vs. Internal Styes
Most styes are external, forming at the base of an eyelash where smaller oil glands sit. These are the ones you can usually see as a visible white or yellow head near the lash line. Internal styes develop deeper in the eyelid, inside the larger oil-producing glands that line the inner surface. Internal styes tend to be more painful because they press against the eyeball, and they’re less likely to drain on their own.
What Makes Styes More Likely
Styes are slightly more common in adults between ages 30 and 50, and women get them somewhat more often than men, likely because eye makeup can block gland openings and promote bacterial growth. But the biggest risk factors have to do with everyday habits and underlying health conditions.
Hygiene Habits
Touching or rubbing your eyes with unwashed hands is one of the fastest ways to introduce bacteria to your eyelid glands. Sleeping in eye makeup is another major contributor, since mascara and eyeliner sit directly over the gland openings for hours. Sharing cosmetics with someone who has a stye can spread the infection, because styes are contagious. Old makeup, particularly mascara and liquid eyeliner that’s been open for months, can harbor bacteria even without visible contamination.
Contact lens wearers face added risk if they handle lenses without washing their hands first, or if they wear lenses past their recommended replacement schedule. Wearing contacts during a stye is a poor idea, since a burst stye can trap bacteria underneath the lens against your eye.
Underlying Health Conditions
Several chronic conditions make styes significantly more likely to recur. Blepharitis, a persistent low-grade inflammation of the eyelid margins, is the single biggest predisposing factor. It causes the gland ducts to narrow and the oil they produce to thicken, creating a cycle of blockage and infection. Rosacea affects the same glands, causing them to overproduce a turbid, thick secretion that plugs the openings and can lead to repeated styes or cysts. Seborrheic dermatitis, diabetes (which weakens immune response), and high cholesterol levels all increase the odds as well. Higher cholesterol can actually raise the melting point of the oils your eyelid glands produce, making the secretions more viscous and prone to clogging.
What a Stye Feels Like as It Develops
The first sign is usually a localized tenderness or a gritty, irritated feeling on one part of your eyelid. Within a day, that spot typically becomes red and swollen, and you may notice a small firm bump. Over the next two to four days, the bump grows as pus accumulates, often developing a visible white or yellow center. Your eyelid may swell enough to partially obscure your vision, and the eye on that side often waters excessively.
Most styes come to a head and drain on their own within a week to ten days. Once they drain, the pain drops off quickly and the swelling resolves over the next few days. Styes that don’t drain can sometimes harden into a painless but persistent lump called a chalazion, which may take weeks or months to resolve without treatment.
How to Help a Stye Heal
The most effective home treatment is a warm compress. Soak a clean washcloth in warm (not hot) water, wring it out, and hold it against your closed eyelid for 10 to 15 minutes, three to four times a day. The heat loosens the thickened oil blocking the gland and encourages the stye to drain naturally. Re-wet the cloth as it cools to maintain consistent warmth.
Gently cleaning the eyelid with a mild, tear-free soap or diluted baby shampoo helps keep bacteria from recolonizing the area. Avoid squeezing or popping a stye the way you would a pimple. The eyelid has a rich blood supply, and forcing a rupture can spread infection into surrounding tissue. Over-the-counter pain relievers can take the edge off the tenderness while you wait for the stye to resolve.
Skip eye makeup entirely while you have a stye, even if the bump feels minor. Throw away any mascara, eyeliner, or eyeshadow applicators you used in the days before the stye appeared, since they may be contaminated.
Preventing Styes From Coming Back
If you get styes more than once or twice a year, a daily eyelid hygiene routine can break the cycle. Wash your eyelids each morning with a gentle cleanser, paying attention to the lash line where gland openings sit. Pre-moistened eyelid wipes designed for this purpose are widely available at pharmacies. Replace mascara and liquid eyeliner every two to three months regardless of how much is left, and never share eye cosmetics.
For people with blepharitis or rosacea, managing the underlying condition is the most effective prevention. Warm compresses used daily (not just during a flare) keep the oil glands flowing freely and reduce the chance of blockage. If you wear contact lenses, wash your hands thoroughly before every insertion and removal, and stick to the replacement schedule your eye care provider recommends.