A stye forms when bacteria infect one of the tiny oil glands or hair follicles along your eyelid margin. The result is a red, painful bump that looks and feels like a small pimple. The bacterium responsible is almost always Staphylococcus aureus, a common skin microbe that normally lives on your face without causing trouble. Problems start when that bacteria gets trapped inside a blocked gland.
How a Stye Actually Forms
Your eyelids contain dozens of small glands that produce an oily substance meant to keep your tears from evaporating too quickly. When one of these glands becomes clogged, the oil backs up, and bacteria already present on the skin begin multiplying inside the blocked duct. Your immune system responds with inflammation, and within a day or two you have a swollen, tender lump.
There are two types. External styes, which are far more common, develop at the base of an eyelash follicle in a small oil or sweat gland near the lid margin. Internal styes form deeper inside the eyelid when a meibomian gland (one of the larger oil-producing glands embedded in the lid itself) gets infected. Internal styes tend to be more painful and take longer to resolve because they sit under more tissue.
The Most Common Triggers
Anything that clogs those oil glands or introduces bacteria to the area raises your risk. Here are the usual culprits:
- Touching your eyes with unwashed hands. This is the single most common way bacteria reach your eyelids. Every time you rub your eye or adjust a contact lens without washing up first, you’re transferring skin bacteria directly to vulnerable gland openings.
- Blepharitis. This chronic, low-grade inflammation of the eyelid margin causes the oil glands to thicken and stagnate. It’s the condition most strongly linked to recurring styes because it keeps glands partially blocked at all times.
- Old or shared eye makeup. Mascara wands and eyeliner pencils collect bacteria over time. The FDA recommends discarding mascara three months after purchase, and throwing away any eye cosmetics you were using when an infection developed.
- Contact lens habits. Lenses that aren’t cleaned on schedule, stored in old solution, or handled with dirty fingers can trap bacteria against the lid. Wearing contacts during an active stye is especially problematic because the lens rubs against the swollen area and can spread the infection.
- Leaving eye makeup on overnight. Sleeping in makeup gives bacteria hours of uninterrupted contact with partially blocked pores along the lash line.
Chronic Conditions That Increase Risk
Some people get styes once and never again. Others deal with them repeatedly, and an underlying health issue is often the reason.
Ocular rosacea, a variant of the skin condition rosacea that affects the eyes, is a well-documented driver of recurrent styes. It causes persistent eyelid inflammation, clogged glands, and frequent infections including styes and chalazia. If you notice recurring styes alongside facial redness or a gritty feeling in your eyes, rosacea may be involved.
Uncontrolled diabetes also plays a role. High blood sugar promotes the production of molecules that suppress immune defenses, making it harder for your body to fight off routine bacterial infections at the eyelid. People with poorly managed diabetes are more prone to styes and may find they heal more slowly.
What a Stye Feels Like
A stye typically starts as a small area of tenderness or swelling on one eyelid. Over 24 to 48 hours it grows into a visible red bump, often with a white or yellow center where pus is collecting. The eyelid may feel heavy, watery, or gritty. Some people notice their whole eyelid swells even though the actual infected spot is small. Light sensitivity and a feeling like something is stuck in the eye are common.
Pain is the hallmark that separates a stye from a chalazion, which is a similar-looking lump. A stye is tender to the touch and often throbs. A chalazion, by contrast, is a painless, firm nodule caused by a non-infectious inflammatory reaction to trapped oil. Chalazia sometimes start as styes that didn’t fully drain. They’re annoying but not actively infected.
Home Treatment That Works
Most styes resolve on their own within one to two weeks. The single most effective thing you can do at home is apply warm compresses. The American Academy of Ophthalmology recommends holding a clean, warm washcloth against the closed eyelid for about five minutes at a time, two to four times per day. The heat softens the clogged oil, encourages the gland to drain, and increases blood flow to the area so your immune system can do its job.
A few things to avoid: don’t squeeze or pop a stye the way you would a pimple. The eyelid tissue is delicate, and squeezing can push the infection deeper or spread it to neighboring glands. Don’t wear contact lenses or eye makeup while the stye is active. And keep your hands away from the area between compress sessions.
When a Stye Needs Medical Attention
If warm compresses haven’t made a difference after several weeks, or if the bump is large enough to press on your eye and blur your vision, a doctor can drain it. This is a quick in-office procedure where the bump is opened with a small incision or needle to release the trapped pus. It sounds unpleasant but it’s done under local anesthesia and takes only a few minutes.
Rarely, the infection can spread beyond the stye into the surrounding eyelid tissue, a condition called preseptal cellulitis. The warning signs are hard to miss: the entire eyelid becomes swollen and red, pain intensifies, and fever may develop. If you or a child develops a fever along with eye pain, vision changes, or bulging of the eye, that signals a possible deeper infection called orbital cellulitis, which requires emergency treatment.
Preventing Styes From Coming Back
If you’ve had one stye, your odds of getting another are higher, especially if blepharitis or rosacea is in the picture. A consistent lid hygiene routine is the best defense. That means washing your eyelids gently each morning with warm water or a diluted baby shampoo, keeping your hands clean before touching your face, and replacing eye makeup on a regular schedule.
For contact lens wearers, the rules are straightforward: wash hands before every insertion and removal, use fresh solution every time (never top off old solution), and stick to the replacement schedule your eye doctor gave you. If you tend to fall asleep in your lenses, switching to daily disposables eliminates the overnight bacterial buildup that contributes to infections.
People with recurring styes tied to blepharitis or rosacea often benefit from a daily warm compress routine even when no stye is present. Five minutes of gentle heat each morning keeps the oil glands flowing freely and makes blockages far less likely.