Asthma Triggers

Nearly just as important as knowing the symptoms of asthma, and keeping them in check, is identifying your asthma triggers—and essential part of asthma prevention and avoiding problems that can come with this condition.

An overview of common asthma symptoms.

Asthma triggers, if not avoided, will ultimately lead to symptoms such as:

Common Asthma Triggers

There are several common asthma triggers. What affects your asthma, and to what extent, is highly personal:

  • Indoor triggers
  • Outdoor triggers
  • Foods
  • Exercise
  • Respiratory infections
  • Medications

Let's delve a little into each one.

Indoor Triggers

Americans spend as much as 90 percent of their lives indoors. As a consequence, indoor allergens can play a significant role in worsening asthma. Identifying the indoor allergens affecting your asthma could lead to significant improvements by either prompting you to avoid the triggers or develop a plan (with the help of your healthcare provider) to deal with them. Indoor asthma triggers that may affect you include:

  • Secondhand Smoke: Secondhand smoke, or environmental tobacco smoke, consists of a mixture of both the smoke irritants exhaled by smokers of cigarettes, pipes, or cigars and from the burning tobacco itself. Environmental tobacco smoke contains more then 250 different cancer-causing chemicals such as benzene, vinyl chloride, and arsenic that may irritate your airways and lead to asthma symptoms.
  • Dust Mites: Dust mites are small insects in every home that cannot be seen with the naked eye. The dust mites feed on tiny flakes of skin found on bedding products (mattresses, pillows, bed covers), carpets, upholstered furniture (or anything covered in fabric), and your child's stuffed toys. Dust mites can both trigger asthma symptoms or lead to asthma symptoms in people without a previous history of asthma.
  • Mold: Molds can grow anywhere where moisture is present. Molds commonly grow on wet or damp surfaces in locations like bathrooms, kitchens, and basements. If molds are a problem in your home, controlling moisture may lead to better control of your asthma.
  • Cockroaches and Other Pests: Body parts, urine, and droppings of cockroaches and pests contain specific proteins that can trigger allergy symptoms. It is essential to remove hiding places for pests and keep countertops and other exposed areas free from food and water.
  • Pets: Allergens from your pets' dead skin, droppings, urine, and saliva can trigger asthma. The best way to prevent pets from worsening your asthma is to not allow them in your home. If this is not possible, it is best to have a pet-free area, such as the bedroom, and to clean your house frequently, especially rugs, upholstered furniture, and stuffed toys and animals.
  • Nitrogen Dioxide: Nitrogen dioxide is a gas that comes from gas stoves, fireplaces, or gas space heaters that can irritate the lungs leading to shortness of breath.

Outdoor Triggers

During the spring and fall, airborne pollens and molds commonly trigger asthma symptoms.

  • Pollens: Pollens are small, powdery, granules that are essential for plant fertilization. Weather conditions greatly influence the amount of pollen in the air. Pollen season will vary depending on where you live, but generally lasts from February to October. Pollens from many different kinds of grasses, plants, and trees may trigger allergy symptoms.
  • Molds: There are many molds in the outdoor environment that become airborne, but unlike pollens, do not have a particular season. Many outdoor molds can be found in the soil and outdoor vegetation.
  • Weather: You may notice that the weather significantly affects your asthma symptoms. On days that are hot, dry, and windy, pollen counts will likely be higher, and you may experience more asthma symptoms. Rain may also lead to increased molds that may worsen symptoms. On the other hand, days that are cloudy with very little wind may result in only minimal asthma symptoms. Because you cannot avoid weather like allergens, you must have effective treatment for your asthma.

    Respiratory Infections

    The common cold, influenza, and other respiratory infections may trigger your asthma. While you cannot always prevent a cold, you can do your best and try: Make sure you wash your hands frequently, avoid touching your nose or mouth while in public or when around someone with a cold, and get appropriate immunizations.

    Less Common Asthma Triggers

    Though these triggers are less common, they are no less important.


    A number of different medications may trigger your asthma. If you believe any medication is worsening your asthma, talk with your doctor about whether or not changing your dose or your drug regimen all together is advised. Some of the most common offenders are:

    • Pain medications (aspirin, ibuprofen, naproxen)
    • Beta blockers

    Certain Foods

    Certain food allergies may also trigger your asthma. These reactions are more common in infants and children. Some of the most common are:

    • Fish
    • Shellfish
    • Soy
    • Egg
    • Wheat
    • Peanuts
    • Tree nuts, such as walnuts

    Your doctor may ask you to keep a food diary to help determine if specific foods are worsening your (or your child's) asthma, or allergy testing may be needed to help get a diagnosis.

    If you notice symptoms like wheezing or coughing while exercising, you may have exercise-induced bronchoconstriction, commonly referred to as exercise-induced asthma. About 5 percent of the U.S. population has exercise-induced asthma and will benefit from getting a diagnosis and the appropriate treatment.

    Figuring Out Your Triggers

    In order to determine your asthma triggers, you may need to act like a detective. If you go to your neighbor's house and begin playing with their cat and start wheezing, the cause is fairly obvious. However, it may not always be that easy. Asking yourself the following questions may help:

    1. Do the symptoms occur primarily at home or at work? This may indicate that there is an environmental component you need to find, like molds, dusts, or odors.
    2. Do the symptoms fluctuate with the season? This may indicate a more allergic condition, such as allergic rhinitis or hay fever.

    While identifying the triggers may not always be easy, doing so will help you breathe easier.

    Could It Be Something Else?

    A number of health concerns can lead to symptoms that are similar to asthma. Some of these diseases include:

    • Congestive heart failure (CHF): The heart's pump is unable to provide an adequate blood supply to the rest of the body. In addition to wheezing, patients have shortness of breath, difficulty breathing when laying flat, and swelling in the lower extremities.
    • Pulmonary embolism (PE): While a person with a PE may occasionally have wheezing symptoms, more common symptoms are a sudden onset of shortness of breath and chest pain.
    • Cystic fibrosis: Those with this disorder will usually have poor growth in childhood, cough, and shortness of breath in addition to wheezing.
    • Gastroesophageal reflux disease (GERD): While GERD can be a cause of worsening asthma, GERD can also lead to less common causes of wheezing from recurrent pneumonia or scarring of the lungs.

    When to See Your Doctor

    As someone with asthma, it is very important that you recognize and treat the early warning signs of an asthma attack. Appropriate management early on in an asthma attack may prevent a trip to the ER, an admission to the hospital, or worse. Generally, early warning signs of worsening asthma and an asthma attack include:

    • A drop in peak expiratory flow rate
    • Increased cough
    • Wheezing
    • Chest tightness
    • Some difficulty performing normal daily activities
    • Individual factors you notice over time that indicates worsening asthma or an asthma attack

    You will likely be in the "yellow zone" of the asthma care plan when developing these symptoms. Based on your asthma care plan, follow the instructions about taking extra doses of quick-relief medications and initiating other treatments like a course of oral corticosteroids. Your asthma care plan will have instructions regarding how to proceed and when to call your doctor.

    A Word From Verywell

    If you can avoid asthma triggers, you can avoid a lot of problems that can come with your disease. Asthma is a marathon. There is no cure, but asthma can be managed and symptoms placed under control.

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