Do your eyelids often itch? Are your eyes red, or do you feel a strange, irritating sensation, as if something were hiding there? What if the cause of that stubborn discomfort was far more unexpected than you think?

No, it’s not all in your head—there might be a tiny roommate living in your eyelashes. Invisible to the naked eye, but not necessarily harmless. Curious? Keep reading.

Demodex: the quiet tenant most of us unknowingly share

Nearly 90% of adults host a tiny mite called Demodex. Don’t panic—under normal circumstances, it quietly lives inside hair follicles and sebaceous glands, especially around the eyelashes and on the face. It feeds on dead skin cells and sebum… essentially doing a bit of “natural housekeeping” for you.

There are two main types in humans: Demodex folliculorum, which prefers to settle in the eyelashes, and Demodex brevis, which favors sebaceous glands. When their numbers stay low, there’s no real problem. But when the population grows too large, things can get tricky…

When Demodex takes over: warning signs you shouldn’t ignore

Wondering if this little parasite might be behind your eye troubles? Here are the symptoms that should make you suspicious:

• Persistent itching around the eyes

• A burning or stinging sensation

• Redness and swollen eyelids

• Small crusts or flakes at the base of the lashes

• Eyelash loss or weak regrowth

These symptoms may point to Demodex-related blepharitis, a chronic inflammation of the eyelids. In some cases, it can even lead to conjunctivitis or a form of ocular rosacea. The catch? You can’t diagnose it yourself—only a medical exam (often involving sampling a few eyelashes) can confirm Demodex is the culprit.