Styes form when bacteria, most commonly Staphylococcus, infect one of the tiny oil or sweat glands along your eyelid margin. The bacteria block the gland, oil builds up behind the blockage, and the surrounding tissue swells into a painful, red bump. Most of the time, the bacteria were already living on your skin or inside your nose before they found their way to your eye.
What Happens Inside the Eyelid
Your eyelids contain dozens of small glands that produce oil and moisture to keep your eyes lubricated. When one of these glands gets clogged and bacteria begin multiplying inside it, the result is a stye (the medical term is hordeolum).
There are two types depending on which gland is affected. External styes, the more common kind, start in the glands at the base of your eyelashes. They look and feel like a pimple right along the lash line. Internal styes develop deeper in the eyelid, inside oil glands embedded in the firm tissue that gives your eyelid its shape. Internal styes tend to be more painful and may not be visible on the surface, though you’ll feel a tender lump when you press on the lid.
The Most Common Ways Bacteria Reach Your Eye
The single biggest cause is touching your eyes with unwashed hands. Staph bacteria live on your skin and inside your nose without causing problems, but rubbing your nose and then your eye can transfer those bacteria directly to an eyelash follicle or oil gland. From there, infection can take hold quickly.
Other everyday habits that introduce bacteria to your eyelids include:
- Old or shared eye makeup. Every time you apply mascara or eyeliner, the applicator picks up bacteria from your lash line and deposits it back into the product. Over time, the tube becomes a breeding ground. Mascara and liquid eyeliner should be replaced every four months. Pencil liners can last up to a year. Sharing eye makeup with someone else transfers their bacteria to your eyes.
- Sleeping in contact lenses. Wearing lenses overnight traps bacteria against the eye surface and limits oxygen flow, creating conditions where infection thrives. Reusing old contact lens solution or skipping the step of physically rubbing lenses during cleaning also lets bacteria accumulate.
- Using dirty towels or pillowcases. Bacteria from a stye can survive on fabric. Sharing towels or pillowcases with someone who has a stye, while rarely the cause, is a possible route of transmission.
Who Gets Styes More Often
Styes affect men and women equally and occur in every ethnic group at similar rates. Adults get them more often than children, likely because adults produce thicker skin oils, which clog glands more easily. Adults are also more prone to chronic eyelid inflammation.
Certain health conditions raise your risk significantly. Diabetes and high cholesterol levels both increase the likelihood of developing styes. High cholesterol changes the composition of the oils your eyelid glands produce, making them thicker and more prone to blockage. Diabetes impairs your immune response, so minor bacterial infections that your body would normally clear on its own can gain a foothold.
Chronic Eyelid Conditions and Recurring Styes
If you keep getting styes, the problem is often an underlying condition in the eyelid glands themselves rather than a one-time bacterial exposure. Meibomian gland dysfunction, where the oil glands in your eyelids become chronically clogged or produce abnormal oil, is a major driver of recurring styes and blockages. Over time, untreated gland dysfunction can also cause dry eye disease and ongoing eyelid inflammation.
Blepharitis, a condition where the eyelid margins stay inflamed and crusty, creates a similar cycle. The inflammation disrupts normal gland function, which leads to blockages, which leads to more inflammation. Rosacea, a skin condition that causes facial redness and flushing, is a known risk factor for meibomian gland dysfunction as well. People with rosacea who get frequent styes may benefit from treating both conditions together.
Are Styes Contagious?
Technically, yes, but in practice it’s rare. The Staph bacteria that cause styes can transfer from one person to another through direct contact or shared items like towels and pillowcases. But simply being near someone with a stye won’t give you one. The bacteria need to reach a gland opening on your eyelid and find conditions favorable enough to multiply. Most people who develop styes got the bacteria from their own skin, not from someone else.
Reducing Your Risk
The most effective prevention is simple: keep your hands away from your eyes, and wash them before touching your face. If you wear contact lenses, replace the case at least three times a year, use fresh solution every time (never top off old solution), and physically rub the lenses with solution even if the bottle says “no rub.” Studies consistently show that rubbing is one of the most effective ways to remove protein and bacteria buildup. Give your eyes a break from lenses periodically, and never sleep in them.
For eye makeup, replace mascara and liquid products on a regular schedule and never share applicators. If you’ve had a stye recently, toss any eye products you were using at the time. Reusing contaminated makeup is one of the most common reasons styes come back.
If you get styes frequently, a daily eyelid hygiene routine can make a real difference. Warm compresses held against closed eyelids for five to ten minutes soften hardened oil in the glands and help them drain normally. Gently cleaning the lash line afterward with diluted baby shampoo or a dedicated lid scrub removes debris and bacteria before they can cause another blockage. People with blepharitis, rosacea, or meibomian gland dysfunction often find that making this a daily habit dramatically reduces how often styes return.