Styes are caused by bacterial infections in the tiny oil glands or hair follicles along your eyelid margin. The bacterium responsible is almost always Staphylococcus aureus, a common microbe that lives on your skin and only causes trouble when it gets trapped inside a blocked gland. Most styes resolve on their own within one to two weeks, but understanding what triggers them can help you avoid repeat episodes.
How a Stye Forms
Your eyelids contain dozens of small glands that produce oils to keep your tears from evaporating too quickly. When one of these glands or a nearby hair follicle gets clogged, bacteria that normally live harmlessly on your skin can become trapped inside. The blocked, warm environment lets them multiply, and your immune system responds with inflammation. The result is that familiar red, tender bump.
There are two types. An external stye, which is the more common kind, forms at the base of an eyelash when the infection involves the hair follicle and the small oil or sweat glands right next to it. It usually localizes to the eyelid margin within one to two days and looks like a small pimple. An internal stye develops deeper in the eyelid when one of the larger oil-producing glands (called meibomian glands) becomes infected. Internal styes tend to be more painful and swell toward the inner surface of the lid rather than the outer edge.
Common Triggers and Risk Factors
Anything that clogs your eyelid glands or introduces bacteria to the area raises your risk. The most common everyday triggers include:
- Touching or rubbing your eyes with unwashed hands, which transfers bacteria directly to the eyelid margin.
- Old or shared eye makeup. Mascara and liquid eyeliner are considered safe for about three months after opening. Beyond that, bacteria multiply inside the container. Adding water to dried-out mascara accelerates bacterial growth. Makeup brushes should be washed every seven to ten days.
- Poor contact lens hygiene. Handling lenses with dirty fingers, sleeping in contacts, or reusing old solution can introduce bacteria to the eye area.
- Leaving makeup on overnight, which gives bacteria hours to work their way into follicles and glands while the lids are closed.
Beyond hygiene habits, certain chronic conditions make styes more likely. Blepharitis, a persistent low-grade inflammation of the eyelid margins, keeps the oil glands irritated and partially blocked, creating an easy entry point for infection. Ocular rosacea, a variant of the skin condition rosacea that affects the eyes, is specifically associated with recurrent styes, eyelid infections, and blocked glands. Both conditions tend to run in cycles, which is why some people get styes repeatedly while others never do.
Why Adults Get Styes More Often
Styes can happen at any age, but they’re more common in adults than in children. The likely reason is a combination of factors that converge in adulthood: hormone levels cause the oil glands to produce thicker secretions that clog more easily, and conditions like chronic eyelid inflammation and rosacea become more prevalent with age. Men and women are affected equally, and there’s no difference across racial or ethnic groups.
What a Stye Feels Like
The first sign is usually tenderness or a gritty sensation in one spot on your eyelid. Within a day or two, a visible red bump appears. The area swells, and it can feel warm to the touch. Your eye may water more than usual, and blinking can be uncomfortable. External styes often develop a small white or yellowish head, similar to a pimple, as pus collects near the surface. Internal styes don’t always show a visible head but can cause more diffuse swelling on the inner lid.
Most styes are more annoying than dangerous. They typically peak in pain around day two or three, then gradually drain and shrink over the next week or so.
How to Treat a Stye at Home
Warm compresses are the first-line treatment. Research shows it takes about two to three minutes of sustained heat on the eyelid surface to soften and liquefy the trapped oil inside a blocked gland, which is what allows the stye to drain. The American Academy of Ophthalmology recommends applying a warm compress for about five minutes at a time, two to four times a day. Use a clean washcloth soaked in warm (not hot) water, or a microwaveable eye mask designed for the purpose.
One important caution: don’t apply heat continuously. Prolonged warmth dilates the local blood vessels and can actually increase eyelid swelling instead of reducing it. Short, repeated sessions work better than one long one.
Beyond compresses, keep the area clean, avoid wearing eye makeup until the stye heals, and resist the urge to squeeze or pop it. Squeezing can push the infection deeper into the tissue or spread it to surrounding glands.
When a Stye Needs Medical Attention
Most styes clear up within one to two weeks without any medical treatment. If yours isn’t improving after that window, or if it’s getting noticeably worse, you may need a prescription antibiotic ointment or drops. In cases where the infection has spread beyond the gland into the surrounding eyelid tissue, oral antibiotics are sometimes necessary. If a stye grows very large and won’t drain on its own, a doctor can lance it with a small needle to release the trapped material.
There are a few red flags that signal something more serious than a simple stye. Diffuse swelling across the entire eyelid (rather than a well-defined bump), changes in your vision, pain when moving your eye, or a fever suggest the infection may have spread beyond the surface. Preseptal cellulitis, an infection of the tissue around the eye, can start from something as minor as a stye. If the swelling is so severe you can’t open the lid, or if you notice double vision or your eye appears to be pushed forward, those warrant urgent evaluation.
Stye vs. Chalazion
A chalazion looks similar to a stye but develops differently. While a stye is an active bacterial infection, a chalazion forms when a blocked gland becomes chronically inflamed without significant infection. Chalazia are typically painless, grow more slowly, and sit farther from the eyelid edge. A stye that doesn’t fully resolve sometimes turns into a chalazion as the acute infection fades but the blocked gland remains swollen. Chalazia that persist may need a steroid injection or minor surgical removal, unlike most styes, which drain and heal on their own.
Preventing Recurrent Styes
If you get styes more than once or twice a year, the issue is likely an underlying condition like blepharitis or rosacea that keeps your eyelid glands prone to blockage. Daily lid hygiene can help break the cycle: gently clean the base of your eyelashes each morning with a warm washcloth or commercially available lid scrub wipes. This keeps oil from building up along the lash line where bacteria thrive.
Replace mascara and liquid liner every three months, even if the tube isn’t empty. Never share eye makeup or applicators. If you wear contact lenses, wash your hands thoroughly before handling them and follow your eye care provider’s replacement schedule. These are small habits, but they remove the most common opportunities for bacteria to reach your eyelid glands in the first place.