Allergen-proof mattress and pillow covers (also called encasements) do what they promise on one level: they lower the amount of dust mite allergen in your bed. But large trials found that covers used on their own didn’t improve asthma or hay fever symptoms. The 2020 U.S. asthma guidelines therefore recommend covers only as part of a combined plan, not as a single fix.
This guide explains what the research shows, how to choose covers, and the other bedroom steps that make them worth it. It also covers “anti-allergy” mattresses and pillows. For more, see our dust mite and bedding guides.
Jump to: Quick answer · What the research shows · Covers as part of a plan · Choosing covers · Anti-allergy mattresses and pillows · FAQ
Quick answer
- Covers reduce allergen in the mattress: two 2003 trials in the New England Journal of Medicine found lower dust mite allergen levels with impermeable covers.
- Alone, they didn’t improve symptoms: neither trial found a clinical benefit from covers alone, in 1,122 adults with asthma or 279 people with allergic rhinitis.
- Combined plans work better: the 2020 NAEPP asthma guidelines conditionally recommend covers only as part of a multicomponent plan, for people with asthma who are sensitized to dust mites.
- Pair covers with: weekly hot washes of bedding, low humidity, HEPA vacuuming and fewer dust collectors, as Mayo Clinic recommends.
- Replace old bedding: AAFA suggests replacing pillows every 2 years and mattresses every 10 years.
What the research shows
| Study | Who | What happened |
|---|---|---|
| Woodcock et al., 2003 (NEJM) | 1,122 adults with asthma, about 65% sensitized to dust mites | Impermeable covers lowered mattress mite allergen at 6 months (not at 12). Peak flow and ability to stop inhaled steroids were no better than with ordinary covers. |
| Terreehorst et al., 2003 (NEJM) | 279 people with allergic rhinitis and dust mite sensitization | Impermeable mattress, pillow and duvet covers cut mite allergen in mattresses, but symptoms and nasal tests didn’t improve. |
| Cochrane review, 2008 | 54 trials, 3,002 people with asthma | Physical and chemical dust mite control methods (including 26 trials of mattress encasings) showed no effect on peak flow, symptoms or medication use. |
The trials didn’t pin down why covers lowered allergen without helping symptoms. One possibility is that the bed is only one source: mite allergen is also found in carpets and upholstered furniture, so a single change may not lower total exposure enough.
Covers as part of a plan
The 2020 Focused Updates to the Asthma Management Guidelines, from the National Asthma Education and Prevention Program (NAEPP), conditionally recommend impermeable pillow and mattress covers for people with asthma who are sensitized to or have symptoms from dust mites, only as part of a multicomponent allergen mitigation plan, not on their own. The report gives air purifiers, impermeable covers and HEPA vacuuming as an example combination.
Mayo Clinic’s dust mite plan shows what that looks like at home:
- Encase the mattress, box spring and pillows in allergen-blocking covers.
- Wash bedding weekly in water of at least 130°F (54.4°C), or use a hot dryer for things you can’t wash hot; see does a dryer kill dust mites?
- Keep humidity below 50%.
- Vacuum with a HEPA filter or double-layer bag; see choosing a vacuum for allergies.
- Cut clutter and, where possible, replace bedroom carpet with hard flooring.
- Choose washable stuffed toys and keep them off the bed.
If you’re not sure dust mites are your trigger, get tested first; see how common dust mite allergy is and how it’s diagnosed.
How to choose covers
- Full zippered encasements that enclose the whole mattress, box spring and pillow, not just a fitted top cover.
- Tightly woven fabric. Mayo Clinic describes allergen-proof covers as made of tightly woven fabric that keeps dust mites from escaping.
- Comfortable enough to keep on every night; a cover only helps if you use it.
- Washable. Check the care label; covers collect dust on the outside too.
- Cover the duvet or comforter as well, or choose one you can wash hot. See our guide to allergy-friendly comforters and blankets.
What about anti-allergy mattresses and pillows?
“Anti-allergy” or “hypoallergenic” mattresses and pillows are widely sold, but we couldn’t find trials showing that a particular mattress or pillow material improves allergy symptoms on its own. What matters more is how you use and maintain your bedding:
- Encase whatever you sleep on. A cover is easier to control than the fill inside.
- Prefer washable pillows, whether cotton, synthetic or another fill, so you can wash them hot.
- Replace pillows and mattresses on schedule. The Asthma and Allergy Foundation of America suggests every 2 years for pillows and every 10 years for mattresses. See how often to change your pillow.
- Vacuum the mattress every 1 to 3 months, or more often if you don’t use full encasements, as AAFA suggests.
For a full bedroom routine, read how to sleep better during allergy season.
This guide is general information, not medical advice. Read our medical disclaimer.
Frequently asked questions
Do dust mite covers really work?
They lower dust mite allergen in the mattress, but trials found that covers alone didn’t improve asthma or hay fever symptoms. U.S. asthma guidelines recommend them only as part of a broader plan that includes washing, humidity control and HEPA vacuuming.
Should I buy allergy covers for my mattress and pillows?
If you’re allergic to dust mites, they’re a reasonable part of a combined plan. Don’t expect covers alone to fix your symptoms; pair them with weekly hot washes, low humidity and other steps.
Are anti-allergy mattresses worth it?
We couldn’t find evidence that a specific mattress type improves allergies by itself. Encasing your current mattress and keeping humidity and dust low is a proven, cheaper starting point.
How often should I replace pillows if I have allergies?
AAFA suggests replacing pillows every 2 years and mattresses every 10 years, and vacuuming mattresses every 1 to 3 months if they aren’t fully encased.
Do I need to wash allergy covers?
Yes. Follow the care label. Wash your sheets, pillowcases and blankets weekly in hot water, and wash the covers themselves regularly.
Sources
- Woodcock A, Forster L, Matthews E, et al. Control of exposure to mite allergen and allergen-impermeable bed covers for adults with asthma. N Engl J Med. 2003;349(3):225-236.
- Terreehorst I, Hak E, Oosting AJ, et al. Evaluation of impermeable covers for bedding in patients with allergic rhinitis. N Engl J Med. 2003;349(3):237-246.
- Gøtzsche PC, Johansen HK. House dust mite control measures for asthma. Cochrane Database Syst Rev. 2008;(2):CD001187.
- NAEPP Coordinating Committee Expert Panel Working Group. 2020 Focused Updates to the Asthma Management Guidelines. J Allergy Clin Immunol. 2020;146(6):1217-1270.
- Mayo Clinic Staff. Dust mite allergy: Diagnosis and treatment. September 12, 2025.
- Asthma and Allergy Foundation of America. Dust mite allergy.
Last reviewed: October 21, 2026.
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