A stye forms when bacteria, almost always Staphylococcus aureus, infect one of the tiny oil or sweat glands along your eyelid margin. The process typically starts with a blocked gland, and the trapped secretions create the perfect environment for bacteria to multiply. The result is a painful, red bump that looks like a small pimple on or near your lash line.
What Happens Inside Your Eyelid
Your eyelids contain dozens of small glands that produce oils and other secretions to keep your eyes lubricated. When one of these glands gets clogged, its normal output stagnates. That stagnant fluid becomes a breeding ground for staph bacteria, which already live on your skin in small numbers. The bacteria multiply, your immune system responds with inflammation, and within a day or two you have a swollen, tender bump filled with pus.
The thickening and buildup of gland secretions is the key triggering event. Without that initial blockage, the bacteria on your skin surface don’t cause problems. But once the gland’s opening is plugged and its oils sit still, the infection takes hold quickly.
External vs. Internal Styes
Not all styes are the same. The type depends on which gland is affected.
Most styes are external. These develop when an eyelash follicle or one of the small oil glands right next to it becomes obstructed and infected. After a day or two, a small yellowish pustule appears at the base of an eyelash, surrounded by redness and swelling. You may notice tearing, light sensitivity, or a feeling like something is stuck in your eye.
Internal styes are less common and more uncomfortable. These form deeper in the eyelid when one of the larger oil-producing glands embedded in the eyelid tissue gets infected. Because the infection sits behind the lid rather than on its edge, you won’t see a visible pimple from the outside. Instead, the inner surface of the eyelid shows a small raised area or yellow spot. Internal styes can cause more intense pain and swelling, and in some cases may bring on a low fever or chills.
In the first couple of days, external and internal styes can look identical. The distinction becomes clearer as the bump either surfaces near the lash line or stays buried within the lid.
Why Some People Get Styes Repeatedly
If you’ve had more than one or two styes, a chronic condition called meibomian gland dysfunction may be the underlying cause. This happens when the oil glands in your eyelids consistently produce thickened secretions that block their own openings. The glands become chronically inflamed, and repeated infections follow. Recurring styes and persistent lid blockages are hallmark signs of this condition.
Blepharitis, a chronic inflammation of the eyelid margins, is closely linked to the same cycle. Blepharitis creates an environment of ongoing irritation and bacterial overgrowth along the lash line, which increases the risk of gland dysfunction and makes styes far more likely. The two conditions often feed each other: gland dysfunction contributes to blepharitis, and blepharitis makes gland blockages worse.
Common Triggers and Risk Factors
Certain everyday habits significantly increase your chances of developing a stye:
- Touching your eyes with unwashed hands. This transfers staph bacteria directly to your eyelid glands.
- Sleeping in your makeup. Makeup that stays on overnight traps bacteria against the eyelid and clogs the gland openings.
- Using old or expired eye makeup. Mascara, eyeliner, and eyeshadow accumulate bacteria over time. Old products can harbor enough bacteria to trigger an infection. Replace eye makeup every three to six months.
- Poor contact lens hygiene. Handling lenses without clean hands or not disinfecting them properly introduces bacteria to the eye area.
- Rubbing your eyes. This pushes bacteria and irritants into the gland openings and can physically damage the delicate lid tissue.
- Sharing eye makeup. Bacteria transfer easily between users through shared applicators and products.
Any of these habits can set up the initial gland blockage that allows an infection to develop. For people who already have blepharitis or gland dysfunction, even minor triggers can be enough to start one.
How a Stye Progresses
A stye typically announces itself with tenderness and slight swelling at the lid margin. Over the first one to two days, the area becomes more swollen and red as the infection builds. An external stye will usually come to a head, forming a visible white or yellow point near the base of a lash. At that stage, it often drains on its own within a few days and the swelling subsides. Most styes resolve within one to two weeks without any medical treatment.
Warm compresses are the most effective way to speed this along. Holding a clean, warm, damp cloth against the closed eyelid for 10 to 15 minutes several times a day helps soften the clogged material in the gland and encourages the stye to drain naturally. Squeezing or popping a stye is a bad idea. It can push bacteria deeper into the tissue and worsen the infection.
Are Styes Contagious?
A stye itself is not considered contagious in the way a cold or flu is. You can’t “catch” a stye from sitting near someone who has one. However, it is possible to spread small amounts of bacteria from a stye through direct contact. If you touch your stye and then touch a doorknob, towel, or pillowcase, staph bacteria can transfer. Washing your hands before and after touching your face, and changing pillowcases frequently while you have a stye, keeps the risk minimal. Reusing contaminated makeup products or applicators after a stye clears can also reintroduce bacteria and trigger a new one, so replacing any eye products you used during the infection is a smart move.
Preventing Styes
Daily eyelid hygiene is the single most effective prevention strategy, especially if you’re prone to them. Gently washing your eyelids each day removes excess bacteria and keeps the gland openings clear. You can use a clean washcloth with warm water or a commercially available lid scrub. Periodic warm compresses, even when you don’t have a stye, help keep oil glands flowing freely and prevent the buildup that leads to blockages.
Beyond lid care, the basics matter: wash your hands before touching your eyes, remove all eye makeup before bed, replace mascara and eyeliner regularly, and keep contact lenses properly disinfected. If you get styes frequently despite good hygiene, the issue may be an underlying gland dysfunction that benefits from more targeted treatment.