Is Your Heater Triggering Your Eczema?

By Diane Angela Fong, ND

Do your eczema or allergy symptoms seem to get worse in the winter? Are you turning on your heater to stay warm? If so, your HVAC system could be contributing to your flare-ups. As it circulates air through your home, your HVAC system may unknowingly spread hidden irritants like dust mites, mold, and other toxins—common triggers for eczema and allergies.

In this blog, we’ll uncover how your HVAC system might be impacting your skin, dive into research on these hidden culprits, and share practical tips to improve your air quality and protect your skin this winter.

What is an HVAC System?

HVAC stands for Heating, Ventilation, and Air Conditioning. Think of it as the lungs of your home—it regulates temperature, filters and circulates air, and helps maintain indoor comfort.

During the winter, HVAC systems are often used for heating, but they also circulate air during the summer when cooling systems are on or when the fan is used for ventilation. This year-round circulation means your HVAC system can consistently spread hidden allergens like dust mites and mold if it isn’t properly maintained.

When Does an HVAC System Circulate Air?

When Heating or Cooling is On: Your HVAC system actively circulates air whenever the heater or air conditioner is running. This ensures that heated or cooled air is distributed throughout your home.
When the Fan is On:Many systems allow you to run the fan independently of heating or cooling. This mode is often used for ventilation or to keep temperatures consistent but still circulates whatever is in the ducts.
Continuous Circulation:Some modern HVAC systems offer a continuous circulation mode, where the fan runs 24/7, even if heating or cooling is off. While this can improve ventilation, it may spread allergens if filters or ducts aren’t clean.

In winter, turning on the heater can release built-up dust, mold spores, and other irritants from your HVAC system. However, this isn’t just a seasonal issue. Turning on the air conditioner in summer or using the fan at any time of year can also circulate allergens, making your HVAC system a potential problem throughout the year.

Hidden Culprits in HVAC Systems & Why This Matters for Eczema

Dust Mites

Dust mites thrive in warm, enclosed spaces, including HVAC ducts and filters. Once the system is turned on, it blows these allergens into the air you breathe. Their allergens can irritate sensitive skin, disrupting the skin barrier and triggering eczema flare-ups. Research published in the Journal of Allergy and Clinical Immunology has shown that high concentrations of indoor allergens, like dust mites, are associated with greater sensitization, particularly in children.

Mold

Moisture from condensation or leaks in HVAC systems creates an ideal environment for mold growth. Mold can grow on duct surfaces, fiberglass insulation, or vents and become airborne whenever the system circulates air. Mold spores can irritate eczema-prone skin and worsen respiratory issues. A 2016 study published in Pediatric Allergy and Immunology found that children living in homes with visible mold had a 55% increased risk of developing eczema. A study found that prenatal mold exposure significantly increased the risk of developing atopic dermatitis.

Volatile Organic Compounds (VOCs)

VOCs are chemicals emitted from household products like cleaning agents, paints, and building materials. HVAC systems can recirculate VOCs throughout your home, prolonging exposure and potentially concentrating these irritants in poorly ventilated spaces. A study published in the Journal of Clinical Investigation showed that environmental exposures such as VOCs can influence allergic diseases, including atopic eczema, by promoting oxidative stress and initiating proinflammatory responses.

Pet Dander and Pollen

These allergens often accumulate in HVAC filters and ducts, triggering immune responses that can worsen skin inflammation. Research published in the Journal of Allergy and Clinical Immunology has shown that high concentrations of indoor allergens, like pet dander, are associated with greater sensitization, particularly in children.

Bacteria and Viruses

HVAC systems can harbor and circulate bacterial and viral particles, posing a potential health risk to occupants. These microorganisms stress the immune system and may contribute to inflammatory skin conditions like eczema. A 2021 study analyzed dust samples from HVAC systems in two university buildings and identified diverse bacterial communities, including potentially pathogenic genera such as Mycobacterium, Bacillus, and Cupriavidus. The study also detected 350 associations between bacterial communities and pathogenic or antibiotic resistance genes, highlighting the risk HVAC systems pose to indoor air quality and public health.

Steps to Improve Indoor Air Quality and Protect Your Skin

Clean and Maintain Your HVAC System

Replace Filters Regularly: Use HEPA filters to trap allergens and replace them every 1-3 months.
Schedule Duct Cleaning: Professional cleaning removes accumulated dust, mold, and debris from ducts.
Inspect for Mold and Leaks: Address leaks or visible mold growth promptly to prevent spores from spreading.

Control Humidity Levels

Use a Humidifier: Maintain indoor humidity between 30-50% to prevent dry skin and reduce mold growth.
Fix Condensation Issues: Repair any condensation in the HVAC system to reduce the risk of mold.

Reduce Dust Mites and Allergens

Vacuum with HEPA Filters: Regularly vacuum carpets and furniture to remove dust mites and allergens. See my home recommendations, including mattress vacuums here.
Wash Bedding Weekly & Steam/Vacuum Mattresses: Use hot water to kill dust mites and use allergen-proof covers on pillows and mattresses. See my home recommendations, including clean mattress companies that sell allergen-proof covers, steamers, and mattress vacuums here.

Purify the Air

Use air purifiers with HEPA filters to remove airborne contaminants, including mold spores, VOCs, and dust mites. See my air purifier recommendations here.
An air ionizer can be a helpful addition to your home if you're dealing with poor indoor air quality. Ionizers work by releasing negatively charged ions that attach to particles like dust, mold spores, and allergens, causing them to fall out of the air and reducing what your HVAC system recirculates. However, it’s essential to choose an ionizer that does not produce ozone as a byproduct, as ozone can irritate the lungs and exacerbate respiratory or skin conditions like eczema. Look for models specifically labeled as "ozone-free" or certified by trusted air quality organizations.

Get Your HVAC Cleaned Every Year

This year, as the temperatures began to drop, we started turning on our HVAC system to keep warm. Almost immediately, I started waking up sneezing and feeling congested every morning. It had been over a year since we last cleaned our HVAC system, and it was clear that allergens and irritants had accumulated over time. To avoid this in the future, I’ve decided to make HVAC cleaning a priority, scheduling it every September—before the chill of autumn sets in and we need to rely on the heater.

Proactively cleaning your HVAC system once a year, especially before seasonal use, is one of the best ways to reduce exposure to dust, mold, and other irritants that can worsen eczema and allergy symptoms. Don’t wait for flare-ups or symptoms to arise—schedule regular HVAC maintenance to keep your home’s air clean and safe.

If you don't remember the last time you have gotten your HVAC cleaned, and you notice any of the following signs—it may be time to call an HVAC specialist to inspect and clean your system:

Persistent musty odors near vents, which may indicate mold growth.
Dust buildup in or around vents, despite regular cleaning.
Increased eczema or allergy symptoms at home.
Unusual noises or reduced airflow from your HVAC system.

Taking action now can help protect your health and ensure your HVAC system runs efficiently, reducing allergens and irritants that may be contributing to eczema and other health concerns.

Clean Your Body & Environment, Clear Your Eczema

If eczema worsens in winter—or whenever you turn on your heater, air conditioner, or fan, your HVAC system could be the hidden culprit, circulating dust mites, mold spores, VOCs, and other toxins throughout your home. By addressing these triggers through regular HVAC maintenance, improving humidity, and reducing airborne irritants, you can create a healthier indoor environment and reduce eczema flare-ups.

If you or your child have eczema, our team can help you evaluate these root causes of your eczema to support you in healing your skin from the inside out. Start your journey to clear, healthy skin with our Free Resources:

FREE Live Eczema Relief Workshop – Learn strategies to manage eczema naturally
FREE Eczema Root Cause Assessment – Discover possible root causes unique to you
FREE Eczema Relief Guide– Get essential tips for immediate relief

Want a more personalized approach? Book a one-on-one consultation with me at 30% off using code BLOG30 for a tailored evaluation and guidance specific to your needs.

GOT QUESTIONS?

Dr. Fong is going live to discuss this topic on her weekly Live with the Eczema Doc on Wednesday, November 20, at 12:30 PM PST! Watch the live or check out the replay here:

About the Author:

Dr. Diane Angela Fong, ND, is a naturopathic doctor specializing in eczema and chronic inflammatory conditions. She is the CEO and founder of Cleanbody, a wellness company dedicated to treating and preventing chronic diseases. Dr. Fong developed the Cleanbody Method, a transformative three-step process: Evaluate (uncovering the root causes of chronic disease through lab testing and comprehensive assessments), Optimize (strengthening health foundations by addressing nutrition, lifestyle, and toxic exposures), and Support (restoring optimal organ function through targeted healing protocols). Driven by a mission to educate and empower individuals with eczema and other chronic inflammatory diseases, Dr. Fong provides comprehensive support to help patients achieve lasting relief and better health. Learn more at www.cleanbody.health.

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