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Heat can affect anyone. But if you have asthma, heat might affect you even more. You can manage the effects of heat on your asthma with a few steps.

How Can Heat Make Asthma Worse?

Asthma is a chronic disease that causes your airways to get inflamed (swollen), become obstructed or narrowed, and be overreactive to a variety of triggers. All these things can make it hard to breathe. Inflamed airways are more sensitive to irritants and harsh temperatures. These are called triggers. High heat can trigger asthma symptoms.

Here are some of the reasons why heat can trigger asthma symptoms:

  • Breathing in hot air, whether dry or humid, can cause airways to narrow and tighten. Thick, humid air can also make it harder to breathe.
  • Humidity helps common allergens like dust mites and mold thrive, aggravating allergic asthma.
  • Dehydration and an electrolyte imbalance secondary to overheating can worsen asthma symptoms.
  • Heat fuels asthma triggers such as air pollution, increased ozone levels, and pollen and mold spores. They get worse when the weather is hot and humid1. Particles in the air irritate sensitive airways.

By managing your exposure to heat, humidity, and air pollution, you can reduce your chances of having asthma symptoms when the weather gets hot.

What Is Your HeatRisk?

You can track heat in your area with the HeatRisk tool from the Centers for Disease Control and Prevention (CDC). This is a health-based heat forecast that combines health and temperature data to indicate how risky the heat level is in a specific area. Visit and enter your ZIP code to find out the heat risk for your area.

A screenshot of a heat risk website Description automatically generated

How Can I Protect Myself from Heat and Prevent Asthma Symptoms?

When you have asthma, you can reduce your risk of having asthma symptoms when it is hot outside by following these steps.

  1. Stay cool. If possible, stay inside in air conditioning with the windows closed as much as you can. If your home does not have air conditioning, find an air-conditioned public place, such as a library or a cooling center.

  2. Drink plenty of water. Staying hydrated can help your body regulate temperature better. It can also prevent dehydration which is more likely to happen when it’s hot. Dehydration can be dangerous.

  3. Know the symptoms of overheating and asthma. Watch for both symptoms of overheating and of asthma. Some of the symptoms of both conditions are the same.
    • Symptoms of overheating can include:
      • Muscle cramping
      • Unusually heavy sweating
      • Cold, pale and “clammy” skin
      • Fast, weak pulse rate
      • Shortness of breath
      • Dizziness or fainting
      • Headaches
      • Weakness or tiredness
      • Nausea or vomiting
      • Increased thirst
      • Confusion

    • Common signs and symptoms of asthma can include:
      • Shortness of breath
      • Cough
      • Chest tightness or pain
      • Wheeze (a whistling sound when you breathe)
      • Waking at night due to asthma symptoms
      • A drop in your peak flow meter reading (if you use one)
      • Inability to exercise due to increased asthma symptoms

    • If you have symptoms of asthma and/or overheating, get into a cool area, and take your quick-relief medicine. Follow your Asthma Action Plan. Seek medical care if your symptoms are not improving or they are worsening.

  4. Check your local HeatRisk. Use the CDC’s HeatRisk tool to track the risk in your area at The tool shows your heat forecast and air quality. If your area has a high heat forecast or poor air quality, plan indoor activities as much as possible.

  5. Remember to keep taking your asthma medicines. This will help to keep your airways open and clean and your asthma symptoms under control.

  6. Protect your medicines from heat. Hot temperatures can affect medicines like asthma inhalers and epinephrine auto-injectors. Keep them cool in an insulated container when you’re outside. Don’t leave them in your car. Have a way to keep them cool if your area has a power outage.

  7. Talk with your allergist or health care provider. Adjustments can be made to your Asthma Action Plan during hot times of the year, such as peak summer months.

Medical review: July 2024 John James, MD

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1. Clinical Guidance for Heat and Children with Asthma.”, 22 Apr. 2024,


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