Dehumidifier for Allergies: Best Picks for Dust Mites & Asthma

Dust mites and mold are two of the most common indoor allergy triggers, and both depend on humidity. Dust mites do not drink; they absorb water from the air. Mold needs damp surfaces. Lower the humidity and both struggle. That is why allergy organizations recommend keeping indoor humidity below 50%, and why a dehumidifier for allergies can help in a damp home.

A dehumidifier does not filter pollen, pet dander or smoke out of the air. For those you need an air purifier. Many allergy sufferers use both. This guide covers which allergens humidity affects, the target to aim for, and picks for every room.

Sources: ACAAI dust allergy guidance; AAAAI position statement on allergen avoidance; EPA Mold Course.

Dehumidifier for dust mites

The strongest case for a dehumidifier for dust mites comes from research. In a study published in the Journal of Allergy and Clinical Immunology, Arlian and colleagues found that keeping a home's mean daily relative humidity below 50% effectively restricted dust mite populations, even when humidity rose above 50% for 2 to 8 hours a day. The ACAAI (American College of Allergy, Asthma and Immunology) lists keeping home humidity below 50% as a dust allergy management step, and the AAAAI and Mayo Clinic give the same figure.

Humidity is one part of the plan. The AAAAI calls impermeable mattress and pillow covers the most effective way to cut mite allergen in bedding, and notes that washing bedding at 130F or hotter kills mites, while cold washes remove allergen but let it build back up within about two weeks. Mayo Clinic suggests at least 15 minutes in a dryer above 130F for items you cannot wash hot.

Best dehumidifiers for allergies compared

Best dehumidifier for asthma

There is no special asthma dehumidifier. The best dehumidifier for asthma is one sized for the room (use the chart below), set to a target between about 40 and 50%, and kept clean. Two things matter more for people with asthma than for most buyers:

• Do not over-dry. Mayo Clinic recommends keeping indoor humidity between 30% and 50%. Below that range, low humidity can irritate the nose and throat.
• Keep the unit clean. Empty and wipe the bucket regularly and wash the filter as the manual says. A neglected bucket can grow mold, which is the opposite of what you want.

Sources: EPA Mold Course, Chapter 2 ("below 60 percent, ideally between 30 percent and 50 percent"); ENERGY STAR ("The optimum RH level for a building is generally considered to be between 30% and 50%").

Source: ENERGY STAR dehumidifier buying guidance. ENERGY STAR adds: "it's better to oversize than undersize."

Dehumidifier for stuffy room

A room that feels stuffy and close is often a room that is warm and humid. A dehumidifier for stuffy room air makes it feel fresher by pulling humidity down; at the same temperature, drier air feels more comfortable. A dehumidifier for stuffy nose symptoms is a different story: if your nose is stuffy because of dust mites or mold, lowering humidity can help over weeks. If the air is already dry, a dehumidifier will make it worse. Check the hygrometer first.

Also check ventilation. A stuffy room with a closed door and several people in it may simply need fresh air.

Can a dehumidifier cause a sore throat?

Not directly, but it can if it over-dries the room. A dehumidifier sore throat usually means humidity has dropped below about 30%, which Mayo Clinic says can irritate the nasal passages and throat. Fix it by raising the setpoint to 45 to 50%, using a lower fan speed at night, or turning the unit off in dry winter weather. Most units shut the compressor off once they reach the setpoint, so set the target and leave it there rather than running on Continuous.

Dehumidifier vs air purifier for allergies

If your home is above 50% humidity, start with a dehumidifier. If humidity is already fine and you still react, a purifier is the better buy. For a single small room, a combo like the Tenergy Sorbi does a little of both; for real dehumidifying power, buy two separate machines. See our dehumidifier and air purifier guide for combo picks.