Almost every adult face is home to millions of microscopic mites. These Demodex mites live in the hair follicles and oil glands especially on the nose, cheeks, forehead and eyelashes. They feed on sebum and skin cells, come out at night and go entirely unnoticed by most of the people who carry them. However, in rosacea-prone skin you can find them in far greater numbers. They can also cause non-rosacea skin symptoms. In this article, we’ll explore what Demodex mites are and what the research actually shows about their role in rosacea. We’ll also review the signs of a mite overgrowth and which treatments reduce them.
What are Demodex Mites?
Demodex mites are tiny, eight-legged arachnids that live permanently in hair follicles and sebaceous glands. Two different species live on human skin. The first type, Demodex folliculorum, measures 0.3 to 0.4 mm and lives in the upper part of small follicles, especially around the eyelashes. The second type, Demodex brevis, is smaller and lives deeper, in the oil glands that open into those follicles.
Both types of Demodex mite feed on sebum and skin cells. They avoid light, so they spend the day inside the follicle and move about on the skin surface at night, at a pace of 8 to 16 mm an hour. They pass from person to person by close skin contact. This is why babies pick them up from their parents, and their numbers rise with age as the pores enlarge and produce more oil.
Does Everyone Have Demodex Mites?
Yes, almost everyone does, and having them is normal. Research puts the prevalence at about 84% of people over 60 and close to 100% of those over 70. However, you can find mites at every age in between.
What matters is not whether you have them but how many there are. In healthy skin, the density is usually below five mites per square centimetre. Doctors use that figure as the cut-off. A density above five per square centimetre is called demodicosis. This is the point that the mites start to be linked with symptoms. In plain terms, Demodex mites are like the bacteria or yeast on your skin. A small, stable population is part of normal skin. Trouble starts when there’s an overgrowth or when the immune system starts over-reacting to a normal sized population.
Do Demodex Mites Cause Rosacea?
Demodex mites don’t cause rosacea on their own but you can find them in far greater numbers in rosacea-prone skin. Essentially, they amplify the inflammation in people who are susceptible. The strongest evidence is a meta-analysis of 23 studies covering 1,513 patients with rosacea. Compared with people without rosacea, those with rosacea were about nine times more likely to carry Demodex mites. They also had significantly higher mite density. This was true both for the redness-only type of rosacea and for the bumpy acne-like type.
Skin affected by rosacea has one crucial thing in common. It has an over-active innate immune system, with too much activity in toll-like receptor 2 and in an antimicrobial peptide called cathelicidin. The mites and the bacteria they carry, including one called Bacillus oleronius, activate exactly this pathway. So, in a person whose immune system is prone to over-react, a large mite population is a constant irritant that keeps the inflammation going. In some people. there is also a rare, inherited immune mutation that makes them react strongly to Demodex and develop chronic demodicosis.
What the evidence can’t tell us is which comes first. The studies that count mites in rosacea are comparisons at that moment in time. That means they can’t prove that the mites caused the rosacea rather or if having rosacea increases the number of mites. Inflamed, oily, barrier-damaged skin may simply be a better home for mites. As such, the higher numbers may partly be a consequence of rosacea rather than its cause. That’s why it is better to think of Demodex as an amplifier in a susceptible person but not the cause. This would explain why killing the mites reduces the symptoms but doesn’t cure rosacea. It also explains why some people with dense mite populations never develop rosacea at all.
What are the Signs of a Demodex Overgrowth?
A Demodex overgrowth most often looks like rough, dry, slightly red skin with a fine scale in the pores. There may also be a crop of small bumps and pustules on a face that’s otherwise not particularly greasy. The key thing to note is that it is possible to hve overgrowth without rosacea. The signs of non-rosacea Demodex overgrowth include:
- Pityriasis folliculorum: The skin feels like fine sandpaper, with faint redness, follicular scale and often itching or burning.
- Rosacea-like demodicosis: Papules and pustules that resemble papulopustular rosacea. These may appear more suddenly or more asymmetrically than typical rosacea and without redness or flushing.
- Demodex blepharitis: Itchy, irritated eyelid margins with crusting at the base of the lashes. This is sometimes called cylindrical dandruff. It overlaps with ocular rosacea and is common in older adults.
Doctors may also start to suspect non-rosacea Demodex overgrowth if rosacea hasn’t responded to the usual anti-inflammatory treatments or if you have a flare-up following a course of topical steroids or a period of immune suppression. Dermoscopy or counting mites on a skin surface can confirm the diagnosis. However, in practice, most doctors tend to treat based on the history and appearance. Furthermore they usually treat classic rosacea alongside Demodex overgrowth at the same time. Crucially, they will also try to exclude similar looking conditions like perioral dermatitis and fungal folliculitis that need different treatment.
Which Treatments Reduce Demodex Mites?
Topical ivermectin is the best-evidenced treatment to reduce Demodex mites in rosacea and non-rosacea skin. It works by paralysing and killing the mites. Ivermectin also has a separate anti-inflammatory action of its own. It is a prescription-only medicine licensed for the inflammatory lesions of rosacea in the UK. Clinical trials show it has performed at least as well as metronidazole for papules and pustules. Because the mites live and breed inside the follicle over a cycle of about two weeks, treatment usually requires a course of several months. Most people see the first change at around four weeks with improvement building over months. For severe or widespread demodicosis, a dermatologist may add a short course of oral ivermectin
Other rosacea creams like metronidazole and azelaic acid are anti-inflammatory but have little direct effect on mite numbers. Doctor may switch to or add ivermectin when symptoms haven’t responded to them or use them alongside it. A gentle protective skincare routine is the bed rock of rosacea management. Avoid harsh cleansing, exfoliation and “mite cleanses”. These only disrupt the skin barrier and make the skin more prone to inflammation.
What Can You Do About Demodex Mites Day to Day?
The most useful thing you can do is stop trying to eliminate them and start looking after and supporting your skin. Here are some good skincare habits that can help:
- Keep cleansing gentle and consistent: A mild cleanser twice a day removes excess oil and scale without damaging the barrier. Scrubs, brushes and strong acids make rosacea-prone skin worse and don’t reduce mites.
- Avoid steroid creams on the face: Long-term topical steroids suppress the local immune response and are a recognised trigger for mite overgrowth and rosacea-like eruptions.
- Clean the eyelids if they’re crusted or itchy: Daily lid hygiene and use a diluted tea tree or terpinen-4-ol eyelid treatment if your optician or GP suggests one.
- Don’t blame your pillowcase: Mites live in your follicles and not your bedding. Washing bedding is good hygiene and important but it won’t change your mite count.
- Manage the rest of your rosacea: Daily sunscreen and trigger control reduce the flushing that keeps the skin inflamed.
- Get assessed if bumps persist: Rosacea that hasn’t responded to metronidazole or azelaic acid after 8 to 12 weeks or a sudden eruption of pustules require medical review.
Whilst Demodex mites are a normal part of adult skin, they can wreak havoc in those prone to rosacea. In skin whose immune system is primed to over-react, a large mite population feeds the inflammation behind the redness, bumps and pustules. Ivermectin can be an effective treatment as it reduces mite density and lowers inflammation. If you have persistent rosacea, severe flare-ups or sudden onset skin symptoms, it is best to seek medical review for prompt diagnosis and treatment. Just remember that trigger control and a supportive skincare routine form the backbone of rosacea and Demodex overgrowth management.
At City Skin Clinic, we are passionate about personalised skincare. Through our online clinic, our doctors design custom topical rosacea treatments using ingredients like ivermectin, metronidazole, azelaic acid and niacinamide where appropriate. To get started, book a virtual video consultation or use our online consultation form. The journey towards great skin starts here.
This article is intended for general informational purposes only and is not a substitute for medical advice, diagnosis or treatment. Always consult a qualified medical provider for any medical concerns or questions you might have.
