If your nose starts to clog the minute you step into a dusty room or out into a pollen-covered world, you aren't alone. Roughly 26 million Americans live with asthma, and about 7 to 8 percent of U.S. adults experience allergic reactions that can turn an ordinary room into a sneeze-fest.
What many people overlook is that the moisture floating invisibly in indoor air could be making these issues even worse. High relative humidity (RH) supercharges the growth of mold, dust mites, and bacteria, while low RH dries out nasal passages and irritates already-inflamed airways.
You may already know that HEPA air purifiers remove sniffle-causing allergens and dust from your air. They're the best line of defense against indoor air quality issues. But did you know that a dehumidifier can help too? The key is keeping your humidity at a healthy and optimal level.
Here are three ways popular dehumidifiers can keep your allergy symptoms in check.
How Dehumidifiers Influence Allergy and Asthma Symptoms
A dehumidifier pulls moist air over a chilled coil, condenses the water vapor, and returns drier air to the room, lowering RH within hours. Keeping your humidity in the sweet spot, between 45 and 50 percent, deprives common allergens of the damp conditions they need to thrive.
Important Reality Check: Do Dehumidifiers Alone Help With Allergies and Asthma?
In the interest of complete transparency, the answer to this question is: We don't fully know, but possibly no.
Clinical trials of dehumidifiers as a stand-alone asthma or allergy treatment are limited and show mixed results, but most researchers are skeptical about the connection. A landmark randomized trial two decades ago found no consistent change in lung function despite lower mite counts, and other more recent studies continue to rate evidence as inconclusive.
However, the link between lower relative humidity and reduced mold growth and dust-mite populations has been repeatedly confirmed, and those are the very triggers that provoke wheezing and sneezing. So, while no device can replace medication or allergist-guided care, will a dehumidifier help with allergies? It reliably removes two heavyweight triggers, making it a valuable piece of an integrated plan, and if you've suffered with allergies for long, anything is worth trying.
1. Dehumidifiers Prevent Indoor Mold
Mold spores are everywhere, lying dormant until humidity and other conditions allow them to spread and thrive. In damp bathrooms, basements, or closets, colonies spring to life in as little as 24 to 48 hours and release mycotoxins that can inflame lungs, skin, and sinuses, especially in people with asthma. The CDC notes that mold exposure can worsen existing asthma or even contribute to a new-onset disease.
Running a dehumidifier long enough to maintain humidity levels at 45 to 50 percent starves mold of the moisture it needs. A dehumidifier's built-in or wired humidistat automates shut-off once the target is reached, and draining condensate to a floor drain avoids a standing-water reservoir, which also invites mold growth.
2. Dehumidifiers Keep Dust-Mite Populations in Check
Dust mites are microscopic relatives of spiders that feast on skin flakes and thrive when the relative humidity stays above 50 percent. Their airborne waste particles and body fragments are potent asthma triggers. AAFA reminds homeowners that "most dust mites die in low humidity levels", recommending RH be kept under 50 percent.
A dehumidifier for allergies and asthma is thus a practical defense, second only to a quality HEPA air purifier. Lower RH dries mite bodies and desiccates the micro-habitats deep in mattresses, carpets, and upholstery where they nest.
To boost results:
- Launder bedding weekly in water hotter than 130 degrees F.
- Encase mattresses and pillows in allergen-proof covers.
- Vacuum with a sealed HEPA unit two to three times a week.
Keeping RH low does not eliminate the need for these steps, but it may force dust mites into population decline, so each cleaning pass removes more of them.
3. Target Crawl Space and Basement Humidity
Crawl spaces and basements sit below grade, where soil moisture diffuses through concrete and raises indoor RH, even when upstairs feels comfortable. That trapped moisture seeps upward, boosting whole-house RH and ferrying musty odors, mold spores, and mite debris into living areas.
Installing a crawl-space or basement-rated dehumidifier (often capable of removing 70-120 pints/day and plumbed for continuous drainage) keeps sub-floor wood dry, prevents condensation on ducts, and stops spores before they migrate. For best results:
- Seal vents and rim joists to block humid outdoor air.
- Use a condensate pump or a gravity drain so the unit can run 24/7.
- Invest in Crawl Space Encapsulation; a foolproof method for preventing humidity issues.
- Pair with a sump pump and vapor barrier if groundwater intrusion is a problem.
Homeowners who adopt this strategy frequently report fewer upstairs musty odors and a noticeable dip in allergy flare-ups. This additional proof shows that managing "hidden" micro-climates amplifies the benefits of allergies and dehumidifiers working together.
More Humidity Considerations
Too little humidity (less than 30 percent) can backfire, drying mucous membranes and triggering nosebleeds, cracked skin, or greater susceptibility to respiratory infections. The sweet spot remains at 45 to 50 percent RH, balancing mold and mite control with airway comfort.
Unsure about your home's true air quality? Professional IAQ testing, or use of an Air Quality Test Kit or Air Quality Monitor, can uncover hidden problems, formaldehyde off-gassing, combustion by-products, or elevated particulate matter that a dehumidifier alone cannot solve. If these methods indicate a problem, consider investing in a quality air purifier by reading our guide, 5 Things to Consider When Buying an Air Purifier.
And remember: persistent or worsening allergy or asthma symptoms should prompt a visit to a certified doctor or allergist, not just a trip to the pharmacy.
Choosing the Right Size Dehumidifier
Choosing the right size dehumidifier is serious business. If you pick one that's too small, then your humidity issues will linger in spaces the device can't reach. Or if it's too large, then you'll over-dry your space while driving up your energy bill needlessly.
But generally speaking, you will want to measure the space you're dehumidifying (in square feet), note baseline RH, and pick a unit rated to remove at least 1 pint per square foot of moisture load per day for damp areas. That sizing rule ensures your designated dehumidifier for allergies can actually hold RH below 50 percent. To read more about dehumidifier sizing, check out Sylvane's Guide: How to Size a Crawl Space or Basement Dehumidifier.
Dehumidifier Options for Different-Sized Spaces
Once you've worked out the size of your space, you'll need to pick out a quality dehumidifier model with all the features you need. To help you out with that, we've picked out a few different dehumidifier models that we suggest for small, medium, and large spaces.
Midea Cube 20 Pint Smart Dehumidifier - Small Spaces
- Sizing: Up to 300 square feet
- Control Features: Onboard touch button controls. App connected Wi-Fi controls.
- Efficiency: Energy Star Certified
- Installation Considerations: Portable, with nesting bucket design.
Why We Recommend It: This compact cube dehumidifier has one of the most interesting and unique designs we've ever seen. The main body of the dehumidifier nests into its own collection bucket, allowing you to choose between a continuous drain function or a collection-bucket style dehumidifier. Combined with the innovative design, energy efficiency, and easy-to-use features, you have an ideal dehumidifier choice for small spaces in homes where people suffer from asthma.
Shop All Dehumidifiers for Small Spaces
Santa Fe Compact70 Crawl Space Dehumidifier - Medium Spaces
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- Sizing: Up to 2,200 square feet.
- Control Features: Simple dial controls.
- Efficiency: Energy Star Most Efficient. Removes 4.1 pints/kWh used.
- Installation Considerations: Freestanding, ducted, or hanging Installation.
Why We Recommend It: Probably one of the most popular dehumidifier models sold by Sylvane, the Santa Fe Compact70 is an all-around great choice for reliable and efficient dehumidification for controlling allergy symptoms in medium-sized spaces. It offers three different configurations for flexible installation, an unbeatable 6-year warranty, and North American quality craftsmanship.
Shop All Dehumidifiers for Medium Spaces
AprilAire E080 80-Pint Energy Star Dehumidifier - Large Spaces
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- Sizing: Up to 4,000 square feet.
- Control Features: Integrated digital controls. An optional Wi-Fi model is available.
- Efficiency: Energy Star Most Efficient. Removes 2.35 liters/kWh used.
- Installation Considerations: Freestanding or ducted Installation.
Why We Recommend It: When it comes to whole-home dehumidification, AprilAire models are almost always at the top of our list, due to their quality, robust durability, and high capacity. The AprilAire E080 consistently removes 80 pints of moisture per day with Energy Star-rated efficiency, making it ideal for large spaces and whole homes where controlling allergens and asthma-inducing particles is a priority.
Shop All Dehumidifiers for Large Spaces
Other Air-Quality Solutions that Complement a Dehumidifier
A dehumidifier tackles moisture, and a HEPA air purifier captures the allergen particles left behind. Add an energy-recovery ventilator (ERV) or heat-recovery ventilator (HRV) to bring in fresh outdoor air without losing energy, keep HVAC filters clean, and schedule professional duct cleaning every three to five years. Together, these measures form a holistic plan that outperforms any single"gadget fix."
How do Dehumidifiers Help Relieve Allergies and Asthma?
Dehumidifiers relieve allergy and asthma by helping stop mold growth, eliminating dust mites, and focusing on trouble areas in your home like crawl spaces and unfinished basements.
To take the guesswork out of decoding your humidity level, shop for a dehumidifier with a humidistat that continuously measures the humidity in your air. These models will adjust the dehumidifying speed based on the humidistat reading to maintain a healthy level.
Alternatively, you can use a hygrometer to monitor your humidity level, so you'll know if you should run your dehumidifier more or less often. For more tips on how using a dehumidifier helps you manage your symptoms, check out our article How Moisture in Basements and Crawl Spaces Can Affect Your Whole House.
Still need help selecting a dehumidifier to help with your asthma and allergy-related symptoms? Contact one of our product experts at 1-800-934-9194.
