What Causes Asthma? Common Triggers to Know and Tips for Avoiding Them

1. Respiratory infections

Respiratory infections are the most common cause of asthma attacks. Infections from the common cold (rhinovirus), respiratory syncytial virus (RSV), and other viruses can bring on asthma symptoms. 

There may be some overlap in symptoms between asthma and other respiratory infections. Most people with asthma can tell when they have breathing symptoms that are different from their usual asthma symptoms. If that’s not the case for you yet, your healthcare team can help you understand the difference between the two. 

You should also work with a healthcare professional to make a plan for how to treat your asthma symptoms when you get a cold or chest infection.

2. Allergens

Allergens are substances in our environment that we breathe in. For people without asthma, they’re usually harmless. But for those with allergic asthma, they can trigger an overreaction of the immune system and lead to worsening asthma symptoms. Allergens can be found both indoors (home, work, and school) and outdoors.

Examples of allergens include:

• Pollen: This is a natural part of plants that’s a common cause of allergies.

• Animal dander: These are small flecks of pet skin or dried saliva.

• Dust mites: These are bugs so small you can’t see them with the naked eye. Dust mites can live on soft surfaces like carpet.

• Cockroaches: This includes any part of the insect or their droppings.

• Mold: This is a fungus that naturally grows in damp places.

3. Inhaled irritants

Similar to allergens, irritants can be found both indoors and outdoors. They can also make asthma symptoms worse. But irritants are less likely to cause a reaction from the immune system.

Some examples of inhaled irritants include:

• Tobacco smoke: cigarette smoke, firsthand or secondhand

• Other types of smoke: smoke that comes from a wood-burning stove, fireplace, or heater

• Sprays and smells: hair spray, perfumes, paint, or powders

• Air pollution: smog, car exhaust, or wildfire smoke 

• Workplace irritants: dust, chemicals, or cold weather environment 

4. Activities and lifestyle

Some activities and lifestyle choices can bring on asthma symptoms. These include:

• Exercise: Exercise itself can cause asthma symptoms. Or, if exercising outdoors, symptoms can be brought on by other triggers like cold air, pollen, or pollution. There are ways to prevent this, so you probably won’t have to avoid exercise completely. Speak with a healthcare professional about ways to manage exercise-induced asthma.

• Cannabis smoke: Smoking cannabis may be associated with asthma symptoms, according to research. However, the relationship between cannabis smoke and asthma isn’t as clear.

• Sulfites: Additives and preservatives like sulfites can cause adverse reactions, including worsening of asthma symptoms. Sulfites can be found in foods (like dried fruits and processed potatoes) and alcohol (like wine and beer).

5. Medications

Some medications can trigger asthma symptoms. Let a healthcare professional know about any medications you’re taking, especially if you’re taking any of these:

• Beta blockers: These medications are commonly used to treat high blood pressure, abnormal heart rhythms, and glaucoma (in an eye-drop form). When someone has asthma but needs a beta blocker, they can make a decision together with their healthcare team about what treatment is best.

• Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs): In some people, aspirin and other NSAIDs like ibuprofen can cause severe or life-threatening asthma attacks. This is known as aspirin-associated asthma, or asthma-exacerbated respiratory disease (AERD). If you have AERD, you should avoid taking any aspirin or other NSAIDs. 

6. Food sensitivity and additives

Food allergies, especially those that cause anaphylaxis, can bring on asthma. Processed foods, particularly those high in sulfites, can also cause an asthma attack. Some of the most common triggers include:

• Dried fruits and vegetables

• Packaged potatoes

• Wine and beer

• Bottled lime and lemon juice

• Shrimp

• Pickled foods

7. Weather and air quality

Weather and air quality can impact asthma management. Extreme weather tends to irritate the airways and may trigger an asthma attack. Some of the weather conditions that are most likely to cause symptoms include:

• Cold, dry conditions

• High humidity

• Extremely hot temperatures

• Rain, thunderstorms

• Sudden changes in weather

8. Stress and emotions

Being emotionally distraught or psychologically stressed can trigger an asthma attack. One recent study found that higher stress levels were linked with more severe asthma attacks. Experts believe that since stress affects immune function, it can also have a direct effect on asthma. Good stress management should always be a part of the overall asthma treatment plan.

9. Medical conditions

Some medical conditions can make your asthma worse. Treating these conditions (where possible) can help improve your asthma symptoms:

• Rhinosinusitis: This is inflammation of the sinuses, usually caused by allergy or infection. Treating rhinosinusitis — with antihistamines, decongestants, or antibiotics (if needed) — can improve asthma symptoms.

• Gastroesophageal reflux disease (GERD): GERD is a condition where acid from the stomach goes up into the esophagus and throat. This reflux can cause symptoms, such as heartburn, a bitter taste in the mouth, and coughing. In people with asthma and symptoms of GERD, treating GERD can help improve the asthma symptoms.

• Obstructive sleep apnea (OSA): OSA is a condition where your airway becomes blocked during sleep. This can cause you to stop breathing temporarily. OSA can worsen asthma symptoms, and asthma can worsen OSA. Asthma symptoms get better when OSA is treated.

• Obesity: People living with a higher body weight tend to have more severe asthma and more frequent symptoms. In some studies, when people lose some excess weight, their asthma symptoms or lung function improve.

• Anxiety and depression: The link between stress, depression, and asthma isn’t fully understood. If you have asthma and symptoms of depression, it’s a good idea to mention this to a healthcare professional. Improving your mental health may help your symptoms of asthma.

• Hormone changes: About one-third of women with asthma experience worsening symptoms around the time of their menstrual cycle. This relationship isn’t clear, but it’s likely due to hormonal changes.

Identify your asthma triggers

You may be able to identify triggers based on patterns in your symptoms. For example, is your asthma worse outside? Or when you exercise? 

Some people notice that they have more asthma symptoms at work. Some clues that you may have a work-related trigger are that your coworkers have similar symptoms, or your symptoms get better on vacation or on weekends. 

There are a few ways to identify your triggers. These include:

• Keeping a symptom diary (taking note of when you get symptoms and what you were doing)

• Using a peak flow meter (taking note of changes in your baseline)

• Allergy testing (this can give clues or confirm possible triggers)

Reduce your exposure

Some asthma triggers can’t be completely avoided, like getting respiratory infections and hormone changes. But there are things you can do to reduce your exposure to certain triggers. If you’ve had allergy testing already and know what you’re sensitive to, you can avoid these things as much as possible. 

Here are some tips on how to avoid asthma triggers:

• Respiratory illness: Proper handwashing and avoiding people who are sick are good places to start. Experts also recommend getting a flu shot yearly.

• Smoking: It’s very important for people with asthma to avoid tobacco smoke. If you smoke, now’s the time to quit. Symptoms and lung function should improve after you stop smoking.

• Mold: Adults with asthma can feel better after getting rid of dampness and mold in the home. Cleaning regularly, fixing leaky faucets, and turning on an exhaust fan while you shower are easy steps to take. 

• Animals: This one is tricky, especially if you already have a loved furry friend. If you have a pet you just can’t part with, try to keep it out of the room where you spend the most time and vacuum regularly.

• Pests: To keep the bugs away, be sure to dust and vacuum weekly, keep your garbage outside, and never leave food out.

• Dust mites: It’s helpful to keep the humidity in your house at less than 50% and get dust mite covers for your mattress and pillow. Dust, vacuum, and wash your bedding weekly.

• Pollen: During allergy season, stay indoors as much as possible and keep the windows closed if you can.

• Exercise: Warm up before you work out, and try to avoid exercising outdoors when the air quality is poor. Some people may need to use an inhaler (like albuterol) before exercise.

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