The NHS names house dust mites among the things that make atopic eczema worse. The mechanism is not in doubt: the main mite allergen is an enzyme that pulls epithelial junctions apart, and eczema-prone skin is already permeable before it arrives. What is in doubt is whether clearing mites from a bedroom does anything measurable to eczema you already have. A Cochrane review of that question found the evidence "falls far short of a basis for influencing clinical practice" (Nankervis et al, 2015).
The allergen is an enzyme, not a passive particle
Mites do not bite or sting. The allergen is Der p 1, a protein in their faecal pellets and a cysteine protease: an enzyme that cuts other proteins.
Wan and colleagues exposed epithelial cell sheets to Der p 1 and watched the junctions between the cells come apart. Occludin, one of the proteins holding a tight junction shut, "was partially cleaved into products of decreased molecular mass", and ZO-1 was degraded too. After two and a half hours, permeability to mannitol rose roughly twelvefold, opening the route the allergen is thought to travel (Wan et al, 1999). Henriquez and colleagues saw the same thing in sinonasal cells: at 24 hours, electrical resistance across the exposed sheet had fallen to 57% of baseline against 82% in controls, with claudin-1 and JAM-A expression down 70% and 43% (Henriquez et al, 2013).
Both experiments used cultured epithelial cells from the airway, so read them as what the enzyme can do rather than a measurement in skin. The skin-side work is smaller. Studying four people with mite-sensitised eczema and four controls, Pfisterer and colleagues found that "the existing barrier deficiency in the non-lesional skin of AD patients allowed deep penetration of both protein and peptide allergens", where an intact barrier stops most molecules above 500 daltons (Pfisterer et al, 2023). The barrier defect comes first, and the allergen widens it.
Why the bedroom holds the exposure
A bed is the one place you spend seven to nine hours in continuous contact with one reservoir, and it supplies what mites need. They thrive above 50% relative humidity at 18 to 30°C, and the common European species, Dermatophagoides pteronyssinus, prefers humidity above 70% and temperatures near 25°C (Jurkiewicz et al, 2025). Whether yours sits in that range is a hygrometer reading, not a guess.
The bedroom carries a second cost unrelated to allergen. Night-time itch fragments the part of the night the skin repairs in, and the stress and sleep post covers the trial in which one night of lost sleep slowed barrier recovery. That belongs in the same audit as the bedding.
What the trials on removing mites found
Nankervis and colleagues pooled seven randomised trials and 324 participants testing mite reduction as a treatment for existing eczema: "covers for mattresses and bedding, increased or high-quality vacuuming of carpets and mattresses, and sprays that kill house dust mites".
One trial of 60 people found a statistically significant benefit on the Six Area, Six Sign Atopic Dermatitis score over six months, using a mite-impermeable bedding system, an acaricidal spray and high-filtration vacuuming together. The other severity comparisons showed no significant difference. The included studies carried a high risk of bias and the evidence was graded very low quality (Nankervis et al, 2015).
A null result on treatment is not a clearance for the allergen. It says a bundle of measures has not been shown to shift established eczema, the same distinction the trigger tracking post draws.
The measures, ranked by what has been measured
Washing has the cleanest numbers, though they are laundry numbers, not skin numbers. Choi and colleagues put fabric through four wash modes and counted what survived. At 60°C and on a steam cycle, every mite was killed. At 30 to 40°C, between 6.5% and 9.6% were. Allergen followed the same order: Der f 1 remaining after the wash was 26.8% at 30°C, 2.4% at 40°C, 1.3% at 60°C and 0.6% with steam (Choi et al, 2008). Rinse count mattered alongside temperature, the argument for the extra rinse in the detergent and fabric posts.
Encasings are the most-tested single measure, and on their own they were null. Two trials gave bedding encasings alone and found no significant between-group difference. A third pairing encasings with an acaricide found none either. The one positive result came from the three-part package. Vacuuming was tested alone once, full power against low power, and that trial reported no between-group comparison (Nankervis et al, 2015).
Humidity control is inference from mite biology, not a finding from an eczema trial. Holding a bedroom below 50% relative humidity puts it under the range mites are reported to thrive in. It belongs in the room-by-room audit on that basis, not as a treatment.
Whether mites are your trigger at all
Sensitisation is common without being universal. Among 452 people with atopic dermatitis assessed in Hanoi, 29.65% were sensitised to D. pteronyssinus and 26.99% to D. farinae (Nguyen et al, 2026). Most were not.
NICE lists inhalant allergens as one of five trigger categories to identify, and flags inhalant allergy in seasonal flares, in eczema alongside asthma or allergic rhinitis, and in children aged 3 or over with facial eczema (NICE CG57, 2025).
Testing it on yourself is harder than it looks: you sleep in your bedroom before every bad week and every good one, so constant exposure passes a one-directional check whatever it does. Make the bedding changes together, hold them four weeks against a daily severity score, then drop the ones that cost money and watch whether the score moves back.
References
- Nankervis H, et al. House dust mite reduction and avoidance measures for treating eczema. Cochrane Database of Systematic Reviews, 2015;1:CD008426. https://pmc.ncbi.nlm.nih.gov/articles/PMC8407038/
- Wan H, et al. Der p 1 facilitates transepithelial allergen delivery by disruption of tight junctions. Journal of Clinical Investigation, 1999;104(1):123-133. https://pmc.ncbi.nlm.nih.gov/articles/PMC408401/
- Henriquez OA, et al. House dust mite allergen Der p 1 effects on sinonasal epithelial tight junctions. International Forum of Allergy and Rhinology, 2013. https://pmc.ncbi.nlm.nih.gov/articles/PMC3782710/
- Pfisterer K, et al. Non-IgE-reactive allergen peptides deteriorate the skin barrier in house dust mite-sensitized atopic dermatitis patients. Frontiers in Cell and Developmental Biology, 2023. https://pmc.ncbi.nlm.nih.gov/articles/PMC10478000/
- Jurkiewicz K, Jutel M, Smolinska S. Update on house dust mite allergy: principal changes over years. International Journal of Molecular Sciences, 2025;26:5660. https://pmc.ncbi.nlm.nih.gov/articles/PMC12193404/
- Choi SY, et al. Optimal conditions for the removal of house dust mite, dog dander, and pollen allergens using mechanical laundry. Annals of Allergy, Asthma and Immunology, 2008;100:583-588. https://doi.org/10.1016/S1081-1206(10)60060-9
- Nguyen DB, et al. Allergen sensitization in atopic dermatitis: distinction from controls and prediction of respiratory allergies. International Archives of Allergy and Immunology, 2026. https://pmc.ncbi.nlm.nih.gov/articles/PMC13200830/
- National Institute for Health and Care Excellence. Atopic eczema in under 12s: diagnosis and management. NICE clinical guideline CG57, 2025. https://www.ncbi.nlm.nih.gov/books/NBK571009/
- NHS. Atopic eczema: causes. https://www.nhs.uk/conditions/atopic-eczema/causes/