A stye is caused by a bacterial infection in one of the tiny glands along your eyelid. The culprit is almost always Staphylococcus aureus, a common bacterium that lives on your skin and can slip into a gland when it gets blocked by oil, dead skin cells, or debris. The result is a painful, red bump that looks a bit like a pimple right at the edge of your eyelash line.
Most styes resolve on their own within one to two weeks, but understanding what triggered yours can help you avoid the next one.
How a Stye Forms
Your eyelids contain dozens of small glands that produce oil to keep your eyes lubricated. When one of these glands gets clogged, bacteria that normally live harmlessly on your skin can multiply inside the blocked opening. Your immune system responds with inflammation, and the area swells into a tender, pus-filled bump.
There are two types. An external stye develops in the oil or sweat glands right at the base of your eyelashes. These are the most common and the most visible. An internal stye forms deeper in the eyelid, in the oil-producing glands embedded in the eyelid’s inner tissue. Internal styes tend to be more painful and may not be as easy to see from the outside, though they often cause noticeable swelling.
Common Triggers and Risk Factors
Anything that introduces bacteria to your eyelid or blocks those tiny glands raises your risk. The most common triggers are everyday habits you might not think twice about.
- Touching or rubbing your eyes transfers bacteria from your hands directly to the delicate skin of your eyelids. This is the single most frequent cause.
- Old or shared eye makeup is a significant risk. Mascara wands and eyeliner tips touch your lash line and then go back into the product, creating a cycle of contamination. Mascara and liquid eyeliner should be replaced every four months; solid eye pencils can last up to a year.
- Sleeping in makeup gives bacteria hours to feed on the product residue sitting on your lash line. Removing eye makeup every night is one of the simplest ways to lower your risk.
- Poor contact lens hygiene plays a role too. Handling lenses without washing your hands, wearing them past their recommended lifespan, or skipping proper disinfection all increase the chance of bacterial transfer to your eyelids.
Underlying Conditions That Make Styes More Likely
Some people get styes repeatedly, and that often points to a chronic condition affecting the eyelids. Blepharitis, a persistent low-grade inflammation of the eyelid margins, is the most common underlying cause of recurrent styes. It keeps the oil glands irritated and partially blocked, making them vulnerable to infection.
Ocular rosacea is another contributor. This inflammatory condition causes redness, burning, and itching of the eyes and frequently leads to blocked eyelid glands. People with facial rosacea are especially prone. Recurrent styes are listed among its hallmark signs, alongside frequent eyelid infections and persistent eye irritation. If you find yourself dealing with styes more than once or twice a year, one of these conditions may be the reason.
How a Stye Progresses
A stye typically develops over a few days. It usually starts as a sore, tender spot on the eyelid, and within about a day a small bump becomes visible. The eyelid around it may look red and swollen. After a few more days, the bump usually comes to a head and drains pus on its own. Once it drains, the pain drops off quickly and the bump shrinks.
The whole process, from first twinge to full resolution, takes one to two weeks without any treatment. Warm compresses can speed things along. Soak a clean washcloth in warm water, wring it out, and hold it gently against the closed eye for five minutes, several times a day. The heat loosens the blocked oil and encourages the stye to drain naturally. Resist the urge to squeeze or pop it, which can spread the infection deeper into the eyelid.
Stye vs. Chalazion
Not every bump on your eyelid is a stye. A chalazion looks similar but behaves differently. The key distinction is pain: a stye is tender to the touch, while a chalazion is not. A stye is an active bacterial infection. A chalazion is a non-infectious inflammatory reaction that happens when trapped oil irritates the surrounding tissue. It tends to form a firm, painless nodule that grows slowly and can linger for weeks or months without the redness and acute soreness of a stye.
Styes can sometimes turn into chalazia. If a stye doesn’t fully drain, the leftover blocked material can harden into a chalazion over time. If you have a painless lump on your eyelid that isn’t going away after several weeks, that’s likely what you’re dealing with.
When a Stye Becomes Serious
Most styes are harmless annoyances, but in rare cases the infection can spread beyond the gland into the surrounding tissue. This is called preseptal cellulitis, an infection of the skin and soft tissue around the eye. Warning signs include swelling that spreads well beyond the bump, a fever, significant eye pain, vision changes, or a bulging appearance of the eye. These symptoms call for immediate medical attention, especially in children, because the infection can advance deeper into the eye socket if left untreated.
How to Prevent Styes
Prevention comes down to keeping bacteria away from your eyelid glands and keeping those glands clear. Wash your hands before touching your face. Replace eye makeup on schedule and never share mascara or eyeliner. Remove all eye makeup before bed. If you wear contacts, clean and disinfect them properly and replace them according to the recommended schedule.
If you have blepharitis or rosacea, managing those conditions with regular eyelid hygiene, such as daily warm compresses and gentle lid scrubs, reduces the frequency of styes. Keeping the oil glands flowing freely is the most effective long-term defense against blockages that let bacteria take hold.