A stye forms when bacteria, almost always Staphylococcus, infect one of the tiny oil glands along your eyelid margin. These glands normally produce oils that keep your tears from evaporating too quickly, but when one gets blocked and bacteria multiply inside it, the result is a painful, red bump that looks and feels like a small pimple. Most styes resolve on their own within one to two weeks, but understanding what triggers them can help you avoid getting one in the first place.
What Actually Happens Inside Your Eyelid
Your eyelids contain several types of oil-producing glands, and a stye can develop in any of them. The type that forms right at the base of an eyelash is called an external stye. It starts in the tiny sebaceous glands attached to your lash follicles. There are one to two of these glands per eyelash, so there’s no shortage of potential sites for infection.
An internal stye develops deeper in the eyelid, in the larger oil glands embedded in the firm tissue (called the tarsal plate) that gives your eyelid its structure. These glands open along the inner edge of your lid, closest to your eyeball. Internal styes tend to be more painful because the swelling presses against the eye itself. When they drain, they release pus on the inner surface of the lid rather than along the lash line.
In both cases, the sequence is the same: a gland opening gets clogged, bacteria that already live on your skin colonize the trapped oil, and your immune system responds with inflammation. That’s the redness, swelling, and tenderness you feel.
The Most Common Ways Bacteria Reach Your Eyelids
Staphylococcus bacteria are already present on most people’s skin. They only cause a stye when they get pushed into a gland opening. The most direct route is your fingers. Touching or rubbing your eyes with unwashed hands is the single most common way to transfer bacteria to your eyelids, and it’s one of the easiest habits to change.
Contact lenses are a major contributor because they require you to touch your eyes repeatedly. Handling lenses with dirty hands, reusing old solution, or wearing lenses past their replacement schedule all increase the chance of bacterial buildup. If you develop a stye while wearing monthly or bi-weekly lenses, it’s a good idea to discard that pair and replace your lens case so you don’t reintroduce the same bacteria.
Eye makeup is another frequent culprit. Every time you apply mascara, eyeliner, or eyeshadow, the applicator touches both the product and your lid margin, transferring bacteria back and forth. Over time, old makeup becomes a breeding ground for bacteria. Mascara and liquid eyeliner should be replaced every four months. Solid eye pencils can last up to a year. Sharing eye makeup with others multiplies the risk because you’re introducing bacteria your immune system hasn’t encountered.
Skin and Eyelid Conditions That Raise Your Risk
Some people get styes once and never again. Others deal with them repeatedly, and there’s usually an underlying reason. Blepharitis, a chronic inflammation of the eyelid margins, is one of the most common links. It causes the oil glands along your lids to function poorly, leading to more frequent blockages. If you notice persistent redness along your lash line, crusty debris on your lashes in the morning, or a gritty sensation in your eyes, blepharitis may be the root cause of recurring styes.
Seborrheic dermatitis, the same condition that causes dandruff on your scalp, can affect your eyelids too. It leads to oily secretions and swelling that make gland blockages more likely. Rosacea is another connection that often goes unrecognized. People typically think of rosacea as facial redness, but it can also affect the eyes directly. Ocular rosacea causes chronic blockage of the oil glands around the eyes and is a well-established driver of recurrent styes.
Can You Catch a Stye From Someone Else?
Styes are not contagious in the way a cold or pink eye is. You won’t get one by being near someone who has one. That said, the bacteria responsible for styes can, rarely, transfer through shared items like towels, pillowcases, or washcloths. The risk is low, but it makes sense to avoid sharing these items with someone who has an active stye and to wash your own bedding and face towels regularly.
How a Stye Progresses
A stye typically starts as a tender, slightly swollen spot on your eyelid. Over the next day or two, it develops into a more defined bump, often with a visible white or yellow head as pus collects. Most styes come to a head and drain on their own within one to two weeks without any medical treatment.
You can speed things along with a warm compress. A clean washcloth soaked in warm water, held against the closed eye for 10 to 15 minutes a few times a day, helps soften the blocked oil and encourages the stye to drain naturally. Resist the urge to squeeze or pop it. Forcing a stye open can push bacteria deeper into the tissue and make the infection worse.
If a stye doesn’t resolve within two weeks, or if it keeps growing rather than shrinking, it may need to be drained by a doctor. A stye that hardens into a painless lump after the infection clears has become a chalazion, which is a different condition caused by a persistently blocked gland rather than active infection.
Signs That Something More Serious Is Happening
In rare cases, the infection from a stye can spread into the surrounding tissue of the eyelid, a condition called periorbital cellulitis. This causes diffuse swelling and redness that extends well beyond the original bump. If the infection spreads even deeper, into the eye socket itself, it becomes orbital cellulitis, which is a medical emergency.
Warning signs that a stye has progressed beyond a simple gland infection include fever, pain that feels disproportionate to the size of the bump, swelling that spreads across the entire eyelid or around the eye socket, changes in vision, or a feeling that the eye is being pushed forward. These symptoms, especially in children, warrant an immediate trip to the emergency room.
Practical Steps to Prevent Styes
Prevention comes down to keeping bacteria away from your eyelid glands and keeping those glands flowing freely. Wash your hands before touching your face or handling contact lenses. Replace eye makeup on schedule and never share it. Remove all eye makeup before bed so it doesn’t sit on your lash line overnight, slowly working its way into gland openings.
If you’re prone to recurrent styes, a daily warm compress routine can help keep your oil glands from clogging in the first place. Gently cleaning along your lash line with a mild cleanser or diluted baby shampoo on a cotton swab removes the debris and bacterial buildup that set the stage for infection. No single eyelid cleaning product has been shown to be clearly superior to another, so consistency matters more than which product you use.
For people with blepharitis, rosacea, or seborrheic dermatitis, treating the underlying condition is the most effective way to break the cycle. When the chronic inflammation is controlled, the glands function better, blockages happen less often, and styes become far less frequent.