Updated on March 6, 2025.
Don’t be fooled by crystal-clear winter air—asthma doesn’t go away just because the pollen’s gone. For many, the cold weather and seasonal indoor allergies mean more asthma attacks during the holiday season.
“Winter brings the perfect storm of cold and flu season, coupled with indoor allergen irritant exposure,” says Adhuna Mathuria, MD, an allergy and immunology specialist in Aldie, Virginia. On top of the bitter cold, there are asthma triggers all around, including:
- Smoke and soot from the fireplace
- Molds that grow on fresh Christmas trees
- Pet hair and dander
- Dry indoor air from the central heater, and more
Cold and flu season starts as the temperatures drop, too, adds Dr. Mathuria. When kids go back to school, they often bring home viruses, which are some of the most common asthma triggers.
With that in mind, here’s what to know about winter triggers, plus ways to breathe easier when the cold air hits.
Why it’s harder to breathe in the cold
If your asthma symptoms worsen when playing in the snow or exercising outdoors, it’s probably because you’re breathing through your mouth from all the energy and excitement.
Normally, nasal breathing humidifies (moistens) your air, explains Mathuria. But when you’re active, you tend to breathe through your mouth instead. With mouth breathing, the winter air—which is drier to begin with—is pulled directly into your lungs without being moisturized.
That dries and irritates your airways and can trigger bronchospasm, or the tightening of the muscles around your airways, which happens during asthma attacks.
Facing the cold
“When you go outside, humidify the air naturally with a scarf that covers your nose and mouth,” recommends Mathuria. The scarf will trap the condensation from your breath to keep the air warm and moist.
You could also pre-treat yourself before winter activities by taking your rescue inhaler. Just let your lung specialist know if you’re relying on your rescue inhaler for everyday activities since he or she may need to increase the dose of your maintenance inhaler.
You may need to add a warm-up session or slowly ease into your normal exercise routine after the weather changes, too. But that doesn’t necessarily mean you have to stop exercising outside altogether. “The goal is to help you stay as active as possible,” says Mathuria. “Your lung specialist or allergist may be able to treat around your symptoms. He or she may increase or change your medications so you can keep exercising comfortably.”
Tackling winter triggers
In addition to cold weather, winter brings a host of seasonal triggers. Here are expert tips to help you cope with common winter allergens.
The Christmas tree
Consider an artificial tree to avoid this trigger all together. Can’t picture the holiday without fresh evergreen? “There are some Christmas trees that you may be less allergic to than others,” says Mathuria. Take your time when tree shopping and ask the attendant if any options are hypoallergenic.
Also be sure to dry the tree out in your garage for about a week, recommends the American Academy of Allergy, Asthma and Immunology (AAAAI). (You may want to hose it down before drying it out.) Then, shake it out to get rid of dead needles and mold spores before bringing it inside.
The fireplace
Avoid wood-burning fireplaces since about 70 percent of the smoke may re-enter your home—even with the chimney flue open. If you rely on a wood-burning fireplace for heat, get it inspected by a local fire marshal or certified inspector annually. They can make sure it’s working properly and doesn’t contain chemical buildup. Keep the room well-ventilated and opt for a glass fireplace door since screens still let fine particles float back into the room.
The central heater
When you turn on the heat after months of inactivity, you stir up the dust, germs, and particles that have been collecting all summer. Consider getting your heating ducts cleaned before using them. Ducts should be cleaned by professionals who know how to avoid spreading allergens throughout the house.
Air from the central heater can also lack humidity. If dry indoor air is irritating your airways, consider a humidifier, set to 35 to 50 percent humidity. Just be sure to clean it regularly to keep mold and bacteria from growing in the water. If you’re allergic to dust mites, talk to your lung specialist before using a humidifier; dust mites thrive in moist environments.
Furry family members
With pets spending more time indoors, fur and dander can build up on fabrics. Limiting your pet to one area of the house won’t help much because dander can still travel through the air.
Invest in a HEPA filter or a HEPA vacuum instead, which can remove some—but not all—pet allergens. If possible, clear away area rugs and throw pillows, since filters work better in rooms with less fabric. If you have a dog, twice-weekly baths could reduce your symptoms as well, but let your vet know in case frequent baths are not appropriate for your dog’s breed.
“Even steam cleaning the carpets may help,” says Dr. Mathuria. “But steam cleaning can be a double-edged sword because some companies use a lot of water, which can actually promote mold growth. Choose a company that’s ‘allergy-aware’ and uses minimal moisture.”
Prevention is the best medicine
The flu’s the last thing you need when your symptoms are flaring. Get your annual flu shot and wash your hands regularly.
Also, let your healthcare provider know if asthma symptoms are keeping you from the activities and events you love this season. “Asthma shouldn't limit your ability to exercise or participate in athletic activities during the winter,” says Mathuria. “People worry about the limitations that come with asthma. But really, our goal in asthma medicine is to provide complete relief so people don't have to alter their lifestyles dramatically.”
