Demodex mites spread primarily through direct skin-to-skin contact with someone who already carries them. Nearly every adult does. These microscopic mites live in hair follicles and oil glands on the face, and most people pick them up during childhood or early adulthood through close physical contact like cuddling, sleeping in the same bed, or cheek-to-cheek touching. The real question isn’t whether you’ll encounter them, but what makes them multiply to the point of causing problems.
Two Species Live on Human Skin
Humans host two distinct species of Demodex mite, each with a preferred habitat. Demodex folliculorum lives in smaller hair follicles, with a strong preference for eyelash follicles. Demodex brevis burrows deeper, settling near the oil glands connected to hair follicles. Both species feed on skin oils (sebum) and dead skin cells, spending most of their lives head-down inside the follicle.
These mites are tiny enough that you can’t see them without magnification, roughly 0.1 to 0.4 millimeters long. They’re nocturnal, crawling across the skin surface at night to mate before returning to follicles. That nighttime movement is one of the main ways they spread from one area of your face to another and from one person to another during close contact.
Person-to-Person Spread
The dominant transmission route is prolonged skin-to-skin contact. Mites transfer when faces touch, when parents nuzzle their children, or when partners share a bed. Brief, casual contact like a handshake is unlikely to transfer mites because they move slowly and need time to migrate from one host to another.
Shared items can also play a role, though it’s a secondary route. Pillowcases, towels, and makeup applicators that touch the face can carry mites or their eggs between people. Mites and their eggs survive away from the host for only short periods under normal conditions, but depending on temperature and humidity, they can persist on surfaces for up to 15 days. That’s a wide enough window for transfer through shared bedding or facial products that aren’t washed between uses.
Can You Get Mites From Pets?
Dog mites are a different species than human mites, and for years the assumption was that they couldn’t cross over. That assumption is being challenged. A documented case involving a family found that a dog-specific mite species (Demodex cornei) had transferred to an 11-year-old boy, causing red, scaly, mildly itchy lesions on the face, neck, and upper arms. Notably, the dog mite showed a greater tendency to spread across the body than the human-adapted species, which typically stays on the face.
This doesn’t mean every dog owner is at risk. Zoonotic transfer appears to be uncommon and likely requires close, repeated contact with an infected animal. But if you or a family member develop unexplained skin irritation and your dog has been diagnosed with mange (canine demodicosis), it’s worth mentioning the connection to your dermatologist.
Why Almost Everyone Carries Them
Demodex colonization increases steadily with age. Infants are typically born without mites, but acquire them through close contact with caregivers in the first years of life. By adulthood, most people are carriers. A large systematic review found that the highest prevalence occurs in adults over 60, reaching 59%. This isn’t because older adults are doing anything differently. It reflects decades of accumulation plus the gradual changes in immune function and skin oil production that come with aging.
At low densities, these mites cause no symptoms at all. Most people live their entire lives unaware they’re hosts. The mites are considered part of the normal skin microbiome, quietly feeding on sebum without triggering any immune response.
What Causes Mites to Overgrow
The shift from harmless passenger to skin problem happens when mite populations spike beyond what your immune system tolerates. Dermatologists use a density of roughly 5 mites per square centimeter of skin as the threshold where demodicosis (mite-related skin disease) becomes a likely diagnosis.
Several conditions create the right environment for that overgrowth:
- Weakened immune regulation. Anything that suppresses or disrupts your skin’s local immune defenses gives mites room to multiply. Long-term use of topical corticosteroids is one of the most common triggers. Certain biologic medications that alter immune pathways can also tip the balance.
- Rosacea. There’s a strong, well-documented association between rosacea and elevated Demodex densities. The relationship runs both directions: the immune disruption in rosacea-prone skin allows mites to proliferate, and high mite populations may worsen rosacea inflammation.
- Hormonal and metabolic changes. Hypothyroidism, pregnancy, and other shifts in hormone levels have been linked to increased mite proliferation, likely because these conditions alter sebum production and immune function simultaneously.
- Excess oil production. Since mites feed on sebum, oilier skin provides a richer food supply. This partly explains why the nose, cheeks, forehead, and chin are the most heavily colonized areas.
Genetic background also plays a role that isn’t fully understood. Some people seem inherently more hospitable to large mite populations, which is why demodicosis sometimes clusters in families beyond what shared bedding alone would explain.
Signs That Mites Have Become a Problem
At normal levels, you won’t notice anything. When populations grow too large, symptoms typically appear on the face, especially around the eyes, nose, and cheeks. Common signs include persistent redness, rough or sandpaper-textured skin, and a crawling or itching sensation that worsens at night (when mites are most active on the skin surface).
Around the eyes specifically, overgrowth can cause crusty buildup at the base of the eyelashes, chronic eyelid irritation, and lashes that fall out more easily than normal. This presentation is sometimes called Demodex blepharitis and is one of the more recognizable patterns.
The tricky part is that these symptoms overlap heavily with rosacea, seborrheic dermatitis, and other common skin conditions. A dermatologist can confirm elevated mite density with a simple skin scraping or by examining pulled eyelashes under a microscope.
Reducing Your Exposure and Risk
Because Demodex is so widespread, avoiding them entirely isn’t realistic or necessary. What you can control are the factors that let populations get out of hand. Washing pillowcases and face towels frequently limits the reservoir of mites and eggs on surfaces you press against your skin nightly. Avoiding sharing makeup brushes, eyelash curlers, or other tools that contact the face reduces person-to-person transfer of larger mite loads.
Keeping your skin’s oil levels in check through gentle, consistent cleansing helps limit the food supply mites depend on. If you use topical steroids on your face for another condition, be aware that prolonged use is one of the most clearly identified triggers for mite overgrowth. Tea tree oil, in diluted formulations designed for skin use, has demonstrated effectiveness at killing Demodex mites and is an ingredient in several over-the-counter eyelid cleansers marketed for this purpose.
For people who already have symptomatic overgrowth, prescription treatments target both the mites themselves and the underlying inflammation. The process typically takes several weeks because treatment needs to outlast the full mite lifecycle, including eggs already laid deep in follicles that haven’t hatched yet.