A stye starts when one of the tiny oil glands along your eyelid gets blocked, trapping secretions inside and creating the perfect environment for bacteria to multiply. The process typically unfolds over a day or two: what begins as a subtle tightness or tenderness near the lash line quickly progresses into a red, swollen bump that can feel like a pimple on your eyelid.
The Blockage That Triggers Everything
Your eyelids contain dozens of small glands that produce oils to keep your tears from evaporating too quickly. These glands have tiny openings along the edge of your eyelid, and when those openings get clogged, the oily secretions behind them thicken and stagnate. That stagnation is what sets the whole process in motion.
Once flow stops, bacteria that normally live harmlessly on your skin surface find themselves trapped in a warm, nutrient-rich pocket of stalled oil. Staphylococcus aureus is the culprit in roughly 90 to 95 percent of cases. The bacteria multiply rapidly inside the blocked gland, triggering your immune system to flood the area with white blood cells. The result is a small abscess: a contained pocket of immune cells, bacteria, and dead tissue that shows up as that familiar painful bump.
External vs. Internal Styes
Not all styes form in the same place, because different glands can be involved. External styes, which are far more common, develop when an eyelash follicle or one of the smaller oil glands right at the lash line gets infected. You’ll see the bump forming on the outer edge of your eyelid, often centered around a single lash.
Internal styes form deeper in the eyelid, in the larger oil-producing glands embedded in the eyelid tissue itself. These tend to be more painful because they push against the inner surface of the lid, and they’re less visible from the outside, at least initially. You might feel an internal stye before you can see it, noticing a deep ache or pressure when you blink.
What the First Hours Feel Like
The earliest sign is usually a localized tenderness. You might notice a sore spot when you rub your eye or blink, even before any visible swelling appears. Within hours, the area starts to redden and puff up. Many people describe it as feeling like something is stuck in their eye.
Over the next day or so, the bump becomes more defined. External styes often develop a small yellowish or white head near the lash line, similar to a pimple coming to a point. The surrounding eyelid can swell enough to partially close the eye, and your eye may water more than usual. Some people experience mild crustiness along the lashes, especially after sleeping.
Why Some People Get Styes Repeatedly
If you’ve had one stye, you’re more likely to get another, and the reason usually traces back to a chronic condition affecting the eyelid. Blepharitis, a persistent low-grade inflammation of the eyelid margin, is one of the biggest risk factors. It causes the lash line to stay slightly swollen and irritated, which makes the gland openings more prone to blockage and leaves the eyelids more vulnerable to infection.
Seborrheic dermatitis, a skin condition that causes oily, flaky patches, also increases stye risk. The excess oil and inflammation it creates around the eyelids contribute to the same cycle of gland blockage and bacterial overgrowth. People with either condition tend to experience styes as a recurring nuisance rather than a one-time event.
Certain habits play a role too. Touching or rubbing your eyes transfers bacteria from your hands directly to the gland openings. Old makeup is another common contributor. Mascara and liquid eyeliner are generally considered safe for about three months before bacterial levels in the product become a concern. Pencil eyeliners last longer, up to about a year. Using products past these windows, or sharing eye makeup, introduces concentrated bacteria right where styes form. Sleeping in eye makeup is particularly risky because it blocks gland openings for hours overnight.
How a Stye Resolves
Most styes drain on their own within one to two weeks. The bump gradually comes to a head, ruptures (often while you sleep or during a warm compress), and the trapped material drains out. Once that happens, the pain and swelling drop off quickly.
Warm compresses are the standard home treatment: a clean, warm washcloth held against the closed eyelid for five to ten minutes, two or three times a day. The heat softens the thickened oil blocking the gland and encourages the stye to drain naturally. Most ophthalmologists recommend continuing this routine for seven to ten days or until the bump disappears.
If a stye doesn’t respond to warm compresses within about two weeks, or if it hardens into a firm, painless lump, it may have transitioned into a chalazion. A chalazion forms when the blocked gland becomes walled off by scar tissue without fully draining. It’s not infected at that point, just a persistent cyst of trapped oil. Chalazia sometimes need a minor in-office procedure to drain if they don’t resolve on their own.
Stye vs. Chalazion: How to Tell the Difference
In the first couple of days, styes and chalazia can look identical. The key difference is pain. A stye is an active infection, so it’s red, warm, and tender to the touch. A chalazion is an inflammatory reaction to trapped oil without active infection, so it tends to be firm and painless. If a bump on your eyelid hurts, it’s most likely a stye. If it’s been there for weeks and doesn’t hurt, it’s more likely a chalazion.
Timing matters too. Styes develop fast, reaching peak swelling within two to three days. Chalazia grow slowly and can linger for a month or more. A stye that stops hurting but doesn’t go away has often become a chalazion, which is the most common progression when a stye doesn’t fully drain.