What Is Asthma? Symptoms & Causes

Asthma is a chronic lung disease that causes inflammation and narrowing of your airways (bronchi), making breathing difficult. It's a common condition that affects nearly 26 million adults and children in the United States.¹

In this article, we'll discuss what asthma is, its symptoms, and common triggers. Understanding your risk of asthma and the symptoms to look out for can help you get the treatment you need  as quickly as possible. For some people, asthma is manageable, while for others, it can be a life-threatening disease.

What Is Asthma?

Asthma is an inflammatory lung disease that causes your airways to narrow, leading to shortness of breath and other lung symptoms. It's often a life-long condition that you'll need to monitor and treat from time to time. For some people, asthma symptoms are mild and typically don’t interfere with their everyday lives — for others, asthma may be a life-threatening condition.²

In asthma, your airways rnswell and narrow in reaction to an irritating substance or trigger. Somern peoples’ lungs also make extra mucus in an attempt to trap substances rnthat set off their asthma symptoms. Long-term inflammation eventually rncauses thickening of your airways, which can permanently affect your rnability to breathe.

What Causes Asthma?

Doctorsrn and researchers aren’t quite sure what causes asthma, but they believe rnthat the immune system plays a role. Normally, your body’s immune systemrn works hard to fight off foreign invaders like bacteria, viruses, and rnpotential allergens to stop you from getting sick.

However, in rnasthma, your immune system may overreact to certain normally harmless rnsubstances you breathe that cause excess inflammation. Substances that rncause an allergic reaction are known as allergens. Your lungs may react rnto specific allergens that cause your airways to become inflamed and rnnarrow, such as pollen, dust, pet dander, or mold.³

Other common asthma triggers include:⁴

• Nonsteroidal anti-inflammatory drugs (NSAIDs), including ibuprofen (Motrin^®, Advil^®) and naproxen sodium (Aleve^®) (in a certain subset of patients)
• Upper respiratory infections, including the common cold
• Acid reflux or gastroesophageal reflux disease (GERD)
• Extremely dry or cold air
• Smog or air pollution
• Exercise
• Tobacco smoke

Types of Asthma

Therern are several types of asthma that can be broken down based on what rntriggers your symptoms. Most people think of allergic asthma or rnexercise-induced asthma when they think of this lung condition — rnhowever, there are many other triggers to be aware of.

Allergic Asthma

Allergicrn asthma occurs when your airways react to an allergen, causing an rnallergic reaction. Your immune system responds to the allergen by rnreleasing a type of antibody known as IgE, which triggers inflammation.³rn Most allergens that set off your asthma are also responsible for rncausing seasonal allergies in the warm months in temperate climates, or rnyear-round allergies indoors. They include:

• Pollen from trees (spring), grasses (mid-summer), and weeds (late summer through fall until the first frost)
• Dust and dust mites (tiny insects that eat our normally shedding skin in our beds and upholstered furniture))
• Pet dander or skin flakes from cats and dogs
• Mold indoors or outdoors in the fall or damp seasons
• Cockroaches
• Other pests including mice and rats

Exercise-Induced Bronchoconstriction

Somern people with asthma go about their normal days never experiencing any rnasthma symptoms. When they start to run, hike, or swim, they become rnshort of breath or wheeze. This is known as asthma or exercise-induced rnbronchoconstriction (EIB, narrowing of your airways).⁵

It’s estimated that many people with asthma also have EIB.⁵rn Since you’re likely to breathe heavily during exercise, taking in dry rnand/or cold air, it’s more likely to irritate your lungs. Pollen, dust, rnor pollution in the air can also cause irritation.

Occupational Asthma

Occupationalrn asthma develops as the result of exposure to irritating chemicals or rnsubstances from your workplace. Most occupational asthma symptoms go rnaway on their own after you avoid your triggers. Dusts, vapors, gases, rnand fumes from different industries can all irritate the lungs and lead rnto asthma symptoms.⁶

The following occupations are more likely to develop occupational asthma:

• Bakers and those who work in food processing plants (dust from flour, grains, and cereals)
• Those who work with metals or in refineries (nickel, platinum, chromium)
• Farmers, veterinarians, and animal trainers (mites, dander, hair, insects)
• Those who work in plastics and upholstery manufacturing (chemical vapors and dust)
• Textile workers (dust from textiles and cotton)
• Those who work in in painting, roofing (isocyanates)

Medication-Induced Asthma

Didrn you know that taking certain medications can cause asthma symptoms? If rnyou take a pain-relieving nonsteroidal anti-inflammatory drug (NSAID) rnlike ibuprofen (Advil®, Motrin®) or naproxen sodium (Aleve®), or rnaspirin, you may notice you become short of breath or start wheezing. rnOther medications used to treat high blood pressure, such as ACE rninhibitors and beta-blockers, can also trigger asthma or symptoms that rnmimic asthma such as coughing (especially ACE inhibitors).⁷

Ifrn you’re taking an NSAID or blood pressure medication and begin rnexperiencing asthma symptoms, talk to your doctor. Do not stop taking rnyour medications without first consulting your doctor.

Risk Factors for Developing Asthma

Somern factors can increase your risk of developing asthma. Some of these you rncan control, while others you can’t. Knowing your risk can help you takern extra steps to avoid developing asthma or even triggering an attack if rnyou’re already living with the condition. Examples include:⁴

• Having another allergic condition like seasonal allergies (hay fever) or eczema
• Being overweight or obese
• Smoking tobacco products, especially long-term
• Exposure to air pollution, smog, or exhaust fumes
• Living with or being near someone who smokes (secondhand smoke exposure)
• Having a parent or sibling who also has asthma
• Working in a profession that exposes you to chemicals, like manufacturing, farming, or hairdressing

Racern and sex also seem to play a risk in developing asthma. According to thern Asthma and Allergy Foundation of America, female adults are more likelyrn to have asthma compared to male adults. However, male children are morern likely to have asthma compared to female children. Black children and rnadults are more likely to have asthma compared to white children and rnadults.¹ Notably, individuals of Puerto Rican descent have rnthe highest rate of asthma of all demographic groups, especially rncompared to other Hispanics.⁸

Symptoms of Asthma

Whenrn you have asthma, your airways swell and make extra mucus, making it rnhard to breathe. Asthma symptoms can range from mild to severe, rndepending on each person and any triggers. An asthma flare or episode rncan last anywhere from a few minutes to several hours or days. rnEveryone’s symptoms are different, but they can include:⁹

• Feeling like you can’t breathe deeply enough or catch your breath (shortness of breath)
• A wheezing or whistling sound when you breathe
• Chest pain or tightness, which can feel like something squeezing or sitting on your chest
• Coughing, which may bring up extra mucus clogging your airways
• Waking up in the middle of the night feeling short of breath or coughing

Symptoms of an Asthma Attack

Whenrn your asthma symptoms are severe and appear suddenly, it’s known as an rnasthma attack. It’s best to work with your primary care doctor, rnpulmonologist, or allergist to create an asthma action plan to monitor rnyour symptoms and know when to seek treatment. Your asthma warning signsrn may be unique to you, so it’s important to learn what your triggers arern and how to handle them.

During an asthma attack, your rnquick-relief or emergency medications might not help. Signs of an asthmarn attack that require immediate medical attention include:⁹

• Severe shortness of breath
• Having trouble talking, standing, or walking due to shortness of breath
• Extreme chest pain and tightness
• Shallow breathing
• Hunching your shoulders when trying to breathe
• Abnormal breathing speed (too fast or too slow)
• Skin sucking into your body around your ribs or neck, known as chest retractions (more common in children than adults)
• Changesrn in color around your lips, tongue, eyes, and fingernails — skin may rnappear blue on lighter skin tones and white or gray on darker skin tones

Diagnosing Asthma

Ifrn your doctor believes you have asthma, they’ll likely perform a physicalrn exam and run several tests to measure how well your lungs work. There’srn no single test that can diagnose asthma — instead, your doctor will putrn together your medical history and the results of several tests to make arn final diagnosis.

Medical History and Physical Exam

Your doctor will likely start by taking your medical historyrn to learn more about your symptoms and your risk factors. Be sure to rntell them if any immediate family members have asthma, seasonal rnallergies, or other inflammatory conditions or diseases.¹⁰ Your doctor will also ask about the triggers that make your symptoms worse. Some questions they may ask include:

• What medications do you currently take?
• What is your occupation? Are you exposed to any substances that may trigger your symptoms?
• Do you have any pets at home, especially if being around them worsens your symptoms?
• Do your symptoms get worse after eating a certain food?
• Do you currently smoke, or are you a former smoker?
• Do your symptoms get worse when exercising?

Duringrn your physical exam, your doctor will check your temperature, heart rnrate, and blood oxygen level to determine whether an infection is rncausing your symptoms. They’ll also listen to your heart and lungs for rnany signs of wheezing.

Lung Function Tests

Lung function tests — also known as pulmonary function tests — measure how well you breathe and how well your lungs work.¹¹rn Your doctor may use one of several lung function tests to diagnose rnasthma, including spirometry, a methacholine challenge test, and an rnexhaled nitric oxide test.

Spirometry

Spirometry is used rnto measure the amount of air you’re able to breathe in and out. It also rnmeasures how quickly you can push air out of your lungs. Spirometry is rnan important tool for diagnosing many different lung conditions, rnincluding asthma, chronic obstructive pulmonary disease (COPD), and lungrn scarring (pulmonary fibrosis).¹²

On the day of your rnspirometry test, your doctor may have you stop taking certain rnmedications or inhalers that can interfere with the results. Don’t smokern for at least 6 hours before your test as well. At the clinic, a rntechnician will place a plastic clip over your nose and a mouthpiece rninto your mouth that’s connected to a spirometry machine (spirometer). rnYou’ll be asked to breathe in and out of your mouth a few times, rnbreathing as deeply as possible and blowing out as hard and fast as rnpossible.

The spirometer will assess two key meaures of your rnbreathing capacity — forced vital capacity (FVC) and forced expiratory rnvolume (FEV1). Your FVC is how much air you breathe out after taking thern deepest breath in. Your FEV1 is the volume of air you breathe out in 1 rnsecond.

Your FVC and FEV1 are used to calculate a score and rncompare you to other people of similar age, sex, height, and weight.. Anrn abnormal score with a lower FVC or FEV1 may point to an asthma rndiagnosis.

Methacholine Challenge Test

After your initial rnspirometry test, your doctor may also choose to perform a methacholine rnchallenge test. Once your breathing is measured to establish your normalrn FVC and FEV1 values, you’ll be given an inhaler containing the drug rnmethacholine. Methacholine causes your airways to narrow, making it rnharder to breathe.¹³

Your doctor will give you several rnsmall doses of methacholine that increase over time. You’ll use the rninhaler (from which you inhale the methacholine) and then measure your rnbreathing with the spirometer until your ability to breathe drops by at rnleast 20 percent. People without asthma aren’t as affected by rnmethacholine as those with asthma. If your breathing ability drops by 20rn percent or more at a low concentration of inhaled methacholine during rnthe test, you likely have asthma.

Exhaled Nitric Oxide Test

Anrn exhaled nitric oxide test — also known as a fractional exhaled nitric rnoxide (FeNO) test — is used to measure the amount of nitric oxide you rnbreathe out.^14,15 This is a substance created when there’s a rnspecific type of inflammation in your airways that is suggestive of rnasthma (eosinophilic inflammation). A FeNO test is similar to a rnspirometry test but easier to perform. Your nose is closed with a rnplastic clip, and you breathe into a mouthpiece connected to a rnspecialized machine. You’ll take a deep breath in slowly, then breathe rnout at a steady rate until the machine beeps.

Complications of Asthma

Manyrn people living with asthma also deal with other complications that rnimpact their quality of life. For those who wake during the middle of rnthe night with asthma symptoms, it can be hard to get a good night’s rnsleep. You may feel fatigued or sleepy during the day, which can rninterfere with school, work, and other commitments.⁴

Ifrn you have a bad asthma flare or attack, you may also have to take time rnoff work or school to recover. More severe attacks may even require you rnto stay in the hospital for a few days to control inflammation in your rnlungs and bring your breathing back to normal.

Asthma also rnincreases your risk of bacterial and viral lung infections. It can be rnharder for you to fight off the common cold or bronchitis compared to rnothers without asthma.¹⁶

Resources for Living with Asthma

Ifrn you or a loved one is living with asthma, there are countless resources available to you to offer support and more information on living with asthma. Feel free to find an online or in-person community or browse rnthese resources to learn more:

• Asthma Resources for Patients and Caregivers — National Heart, Lung, and Blood Institute
• Patient Resources — American College of Allergy, Asthma, & Immunology
• Allergy & Asthma Network

Sources

1. Asthma and Allergy Foundation of America. Asthma Facts and Figures. March 2023. Accessed from: https://aafa.org/asthma/asthma-facts/
2. National Heart, Lung, and Blood Institute. Asthma: Causes and Triggers. March 24, 2022. Accessed from: https://www.nhlbi.nih.gov/health/asthma/causes
3. Asthma and Allergy Foundation of America. Allergens and Allergic Asthma. July 2022. Accessed from: https://aafa.org/asthma/asthma-triggers-causes/allergic-asthma/
4. Mayo Clinic. Asthma: Symptoms & Causes. March 5, 2022. Accessed from: https://www.mayoclinic.org/diseases-conditions/asthma/symptoms-causes/syc-20369653
5. Asthma and Allergy Foundation of America. Exercise-Induced Bronchoconstriction (Asthma). June 2022. Accessed from: https://aafa.org/asthma/asthma-triggers-causes/exercise-induced-asthma/
6. Johns Hopkins Medicine. Occupational Asthma. Accessed from: https://www.hopkinsmedicine.org/health/conditions-and-diseases/asthma/occupational-asthma
7. Asthma and Allergy Foundation of America. Medicines. August 2018. Accessed from: https://aafa.org/asthma/asthma-triggers-causes/medicines/
8. U.S.rn Department of Health and Human Services Office of Minority Health. rnAsthma and Hispanic Americans. Accessed from: rnhttps://www.minorityhealth.hhs.gov/omh/browse.aspx?lvl=4&lvlid=60
9. Asthma and Allergy Foundation of America. Asthma Signs and Symptoms. July 2021. Accessed from: https://aafa.org/asthma/asthma-symptoms/
10. Mayo Clinic. Asthma: Steps in Testing and Diagnosis. January 6, 2022. Accessed from: https://www.mayoclinic.org/diseases-conditions/asthma/in-depth/asthma/art-20045198
11. American Lung Association. Lung Function Tests. March 7, 2023. Accessed from: https://www.lung.org/lung-health-diseases/lung-procedures-and-tests/lung-function-tests
12. American Lung Association. Spirometry. March 10, 2023. Accessed from: https://www.lung.org/lung-health-diseases/lung-procedures-and-tests/spirometry
13. American Lung Association. Methacholine Challenge Test. March 7, 2023. Accessed from: https://www.lung.org/lung-health-diseases/lung-procedures-and-tests/methacholine-challenge-test
14. American Lung Association. Exhaled Nitric Oxide Test. March 7, 2023. Accessed from: https://www.lung.org/lung-health-diseases/lung-procedures-and-tests/exhaled-nitric-oxide-test
15. Nationalrn Heart, Lung, and Blood Institute. What Is Fractional Exhaled Nitric rnOxide (FeNO) Testing? December 2020. Accessed from: https://www.nhlbi.nih.gov/sites/default/files/publications/FeNO-Testing.pdf
16. Juhnrn YH. Risks for infection in patients with asthma (or other atopic rnconditions): Is asthma more than a chronic airway disease? J Allergy Clin Immunol. 2014;134(2):247-257.e3.