If you have asthma, you may find that your symptoms are affected by the seasons. When the temperature dips, going outside can make breathing more of a chore. Exercising in the cold can bring on symptoms like coughing and wheezing even faster.

Here’s a look at what causes cold-induced asthma and how to prevent attacks during the winter months.

How Does Cold Weather Affect Asthma?

When you have asthma, your airways, or bronchial tubes, swell up and become inflamed in response to certain triggers. Swollen airways are narrower and can’t take in as much air. That’s why people with asthma often have trouble catching their breath.

Winter is an especially hard time for people with asthma. A 2014 study from China that was published in PLoS One found hospital admissions for asthma increased during the winter months. In cold climates such as Lapland, up to 82 percent of people with asthma experience shortness of breath when they exercise in cold weather.

When you work out, your body needs more oxygen, so your breathing speeds up. Often, you’ll breathe through your mouth to take in more air. While your nose has blood vessels that warm and humidify the air before it reaches your lungs, air that travels directly through your mouth remains cold and dry. This is just one way that exercising outdoors in cold weather increases your likelihood of having an asthma attack

Why Does Cold Air Affect Asthma Symptoms?

Cold air is hard on asthma symptoms for several reasons:

Cold air is dry.

Your airways are lined with a thin layer of fluid. When you breathe in dry air, that fluid evaporates faster than it can be replaced. Dry airways become irritated and swollen, which worsens asthma symptoms. Cold air also causes your airways to produce a substance called histamine, which is the same chemical your body makes during an allergy attack. Histamine triggers wheezing and other asthma symptoms.

Cold increases mucus.

Your airways are lined with a layer of protective mucus, which helps remove unhealthy particles. In cold weather, your body produces more mucus, but it’s thicker and stickier than normal. The extra mucus makes you more likely to catch a cold or other infection.

You’re more likely to get sick or be indoors when it’s cold.

Colds, flu, and other respiratory infections tend to circulate during the winter months. These infections are also known to set off asthma symptoms.

Cold air can also drive you indoors, where dust, mold, and pet dander flourish. These allergens set off asthma symptoms in some people.

What Precautions Should People with Asthma Take?

Make sure your asthma is under control before winter arrives. See your doctor to develop an asthma action plan, and then take the medicines your doctor prescribed. You may take medicine every day or just when you need it.

Long-term controller medicines are drugs you take every day to manage your asthma symptoms. They include inhaled corticosteroids, long-acting beta-agonists, and leukotriene modifiers.

Quick-relief medicines are medicines that you only take when you need them, such as before exercising in the cold. Short-acting bronchodilators and anticholinergics are examples of these drugs.

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How to Avoid Asthma Attacks in the Cold

To avoid asthma attacks, try to stay indoors when the temperature dips very low, especially if it’s below 10°F. If you do have to go outside, cover your nose and mouth with a scarf to warm the air before you breathe it in.

Here are a few other tips:

  • Drink extra fluids in the winter. This can keep the mucus in your lungs thinner and easier for your body to remove.
  • Try to avoid anyone who appears to be sick.
  • Get your flu vaccine early in the fall.
  • Vacuum and dust your home often to remove indoor allergens.
  • Wash your sheets and blankets every week in hot water to get rid of dust mites.

To prevent asthma attacks when you exercise outdoors in cold weather:

  • Use your inhaler 15 to 30 minutes before you exercise to open up your airways so you can breathe easier.
  • Carry an inhaler with you in case you have an asthma attack.
  • Warm up for at least 10 to 15 minutes before you work out.
  • Wear a mask or scarf over your face to warm the air you breathe in.

Read more: Stay Active with your asthma action plan »

What Else Can Cause an Attack?

Cold is just one of many asthma triggers. Other things that can set off your symptoms include:

  • tobacco smoke
  • strong scents
  • allergens such as pollen, mold, dust mites, and animal dander
  • exercise
  • stress
  • infections with viruses or bacteria

You’ll know you’re having an asthma attack because of symptoms such as:

  • shortness of breath
  • coughing
  • wheezing, or making a whistling sound when you breathe
  • pain or tightness in your chest
  • trouble speaking

What Can You Do If You Are Having an Asthma Attack?

If you start to wheeze or feel short of breath, refer to the asthma action plan you wrote up with your doctor. Here are some general guidelines for what to do if you have an asthma attack:

  • Take two to six puffs from a quick-acting rescue inhaler. The medicine should open up your airways and help you breathe easier.
  • You may also be able to use a nebulizer instead of an inhaler. A nebulizer is a machine that turns your medicine into a fine mist that you breathe in.
  • If your symptoms are so severe that you can’t speak, take your quick-acting medicine and seek immediate medical attention. You may need to stay under observation until your breathing stabilizes.
  • If your symptoms aren’t severe but they don’t improve with the first few puffs from your inhaler, wait 20 minutes and then take another dose.
  • Once you feel better, call your doctor. You may need to keep taking your quick-acting medicine every few hours for a day or two.

The Takeaway

Your asthma attack should subside once you’ve come in out of the cold and taken your medicine. If your symptoms don’t improve or they seem to get worse whenever you’re out in the cold, you may need to see your doctor to review your asthma action plan. You may need to change medicines or come up with other strategies for managing your condition.