Asthma

Asthma is a chronic lung disease that causes your airways to swell, narrow and fill with mucus, making it hard to breathe. While there is no cure, proper treatment and management can help you live a normal, active life.

What is asthma?
Types of asthma
Symptoms
Causes and risk factors
Common triggers
How asthma is diagnosed
Treatment options
Managing asthma at home
Possible complications

What is asthma?

bronchial asthma

Asthma is a chronic condition (meaning long-term) that affects the airways in your lungs. The airways are tubes that carry air in and out of your lungs^[3]. When you have asthma, your airways can become inflamed and narrowed at times, making it harder for air to flow out when you breathe^[3].

The inflammation makes your airways react to certain things around you, like pollen, exercise or cold air. During these reactions, called asthma attacks, your airways narrow (a process called bronchospasm), swell up and fill with mucus. This makes it hard to breathe or causes you to cough or wheeze^[1].

Asthma affects about 1 in 13 people in the United States, according to the Centers for Disease Control and Prevention. It can start in childhood or develop when you’re an adult^[3]. Millions of people in the U.S. and around the world have asthma^[1]. In 2019, asthma affected an estimated 262 million people worldwide and caused 455,000 deaths^[5].

Types of asthma

There are several types of asthma, depending on what triggers your symptoms^[1]:

Allergic asthma: when allergies trigger asthma symptoms
Cough-variant asthma: when your only asthma symptom is a cough
Exercise-induced asthma: when exercise triggers asthma symptoms
Occupational asthma: when substances you breathe in at work cause you to develop asthma or trigger asthma attacks
Asthma-COPD overlap syndrome (ACOS): when you have both asthma and COPD (chronic obstructive pulmonary disease)

You might have asthma most of the time, called persistent asthma. Or you might feel fine in between asthma attacks, called intermittent asthma^[1].

Symptoms

The main symptoms of asthma are problems with breathing. Symptoms vary from person to person and can be mild or severe^[2]. Common symptoms include^[1]^[2]:

Shortness of breath: feeling like you can’t catch your breath or feeling breathless, as if you can’t get air out of your lungs
Wheezing: a whistling or squeaky sound when you breathe out
Chest tightness, pain or pressure: feeling like something is squeezing or sitting on your chest
Cough: coughing that is often worse at night or early in the morning, making it hard to sleep. Sometimes coughing can be the only symptom

Asthma symptoms usually come and go. They may be worse at night and early in the morning^[2]^[7]. You may have infrequent asthma attacks, have symptoms only at certain times—such as when exercising—or have symptoms all the time^[2].

An asthma attack is when you have severe symptoms and it’s difficult to breathe, which can be life-threatening^[7]. During an asthma attack, the sides of the airways in your lungs swell and the airways shrink. Less air gets in and out of your lungs, and mucus that your body makes clogs up the airways^[8].

Causes and risk factors

Experts aren’t sure exactly what causes asthma^[1]. It is caused by inflammation and muscle tightening around the airways, which makes it harder to breathe^[5].

You might be at a higher risk of developing asthma if you^[1]:

Live with allergies or eczema (a condition called atopy)
Were exposed to toxins, fumes or secondhand or thirdhand smoke (residue left behind after smoking), especially early in life
Have a biological parent with allergies or asthma
Experienced repeated respiratory infections (like RSV) as a child

Asthma usually starts in children, but it can happen at any age^[7]. Young children who wheeze a lot and have frequent respiratory infections that continue beyond 6 years old are at greater risk. Genetics can also play a role in developing asthma. Having a family history of eczema, allergies, or having parents or siblings that have asthma increases risk^[6].

Common triggers

Asthma triggers are anything that causes asthma symptoms or makes them worse. You might have one specific trigger or many^[1]. Symptoms can be triggered by different things including exercise, high levels of air pollution, cold air, or contact with something you’re allergic to, such as pollen, dust, mold or animals^[7].

Common triggers include^[1]:

Allergies: pollen, dust mites, pet dander, other airborne allergens
Cold air: especially in winter
Exercise: especially intense physical activity and cold-weather sports
Mold: even if you’re not allergic
Occupational exposures: sawdust, flour, glues, latex, building materials
Respiratory infections: colds, flu and other respiratory illnesses
Smoke: smoking, secondhand smoke, thirdhand smoke
Stress: physical or emotional
Strong chemicals or smells: perfumes, nail polish, household cleaners, air fresheners
Toxins in the air: factory emissions, car exhaust, wildfire smoke

Asthma triggers can bring on an attack right away. Or it might take hours or days for an attack to start after you’re exposed to a trigger^[1].

How asthma is diagnosed

An allergist (a doctor who specializes in allergies) or pulmonologist (a lung specialist) diagnoses asthma by asking about your symptoms and performing lung function tests^[1]. A doctor or nurse will ask you some questions and listen to your chest^[7].

It can be hard to tell if someone has asthma, especially in children under age 5. The doctor may ask if you cough a lot, especially at night. He or she may also ask whether your breathing problems are worse after physical activity or at certain times of year. The doctor may ask about chest tightness, wheezing, and colds lasting more than 10 days. He or she may ask whether anyone in your family has or has had asthma, allergies, or other breathing problems^[8].

Your provider might determine how well your lungs are working and rule out other conditions with^[1]:

Allergy blood tests or skin tests: These can determine if an allergy is triggering your asthma symptoms
Spirometry: This test estimates the narrowing of your airways by checking how much air you can exhale after a deep breath and how fast you can breathe out^[10]
Peak flow: A peak flow meter is a simple device that measures how hard you can breathe out. Lower than usual peak flow readings are a sign that your lungs may not be working as well and that your asthma may be getting worse^[10]

Lung function tests often are done before and after taking a medication to open your airways called a bronchodilator, such as albuterol. If your lung function improves with use of a bronchodilator, it’s likely you have asthma^[10].

You may also be given a handheld device called a peak flow meter to use at home for a few weeks, to check how well your lungs are working^[7]. Sometimes a blood test may be needed^[7].

Asthma can take some time to diagnose because the symptoms often vary over time and breathing problems can have different causes^[7].

Treatment options

Asthma can’t be cured, but its symptoms can be controlled^[2]. There is no cure for asthma, but it is manageable with proper asthma medications and by avoiding common triggers^[6].

Treatment for asthma usually depends on your age, how serious your symptoms are, and how your body responds to medicines^[12]. The main treatment for asthma is medicines you breathe in using an inhaler. For most people they work well to reduce or prevent asthma symptoms^[7].

Depending on how severe your symptoms are, you may be offered either^[7]:

An inhaler to use only when you get symptoms—this is called an anti-inflammatory reliever (AIR) inhaler
An inhaler to use every day to help prevent symptoms, as well as when you get symptoms—this is called a maintenance and reliever therapy (MART) inhaler
2 separate inhalers—a preventer inhaler to use every day to help prevent symptoms, and a blue reliever inhaler to use when you get symptoms (you should not be given a blue reliever inhaler to use on its own)

Asthma medicines are generally divided into two groups^[12]:

Quick-relief medicines (or relievers) help prevent or ease symptoms during an asthma attack. Common relievers include^[12]:

Inhaled short-acting beta2-agonists (SABAs): open the airways so air can flow through
Oral corticosteroids: reduce swelling in your airways
Short-acting anticholinergics: help open the airways quickly

Long-term control medicines (or controllers) are prescribed to help prevent symptoms. These include^[12]^[17]:

Inhaled corticosteroids: reduce inflammation to help prevent asthma symptoms
Inhaled long-acting beta2 agonists (LABAs): open the airways. LABAs should not be used for long-term asthma control on their own; they should be combined with inhaled corticosteroids
Combination inhalers: combine a long-acting beta agonist with a corticosteroid to help manage asthma symptoms
Leukotriene modifiers: help prevent symptoms

Single maintenance and reliever therapy combines an inhaled corticosteroid and long-acting beta2 agonist for controller and reliever treatments. This therapy is preferred for adults and adolescents because of its effectiveness in reducing severe exacerbations^[15].

Your healthcare provider will probably prescribe a quick-relief inhaler for you to carry at all times. For the treatment to work well, make sure to learn how to use your asthma inhaler correctly^[12].

For patients with severe allergic and eosinophilic asthma, biologic agents may be considered. Omalizumab may be used to decrease severe exacerbations and oral corticosteroid use in patients with allergic asthma. Interleukin-5 and interleukin-4/13 antagonists may be used in patients with severe asthma and a blood eosinophil count of 300 per microliter or more^[15].

Subcutaneous immunotherapy (allergy shots given under the skin) may be considered as an adjunct treatment for individuals five years and older with mild to moderate allergic asthma. However, sublingual immunotherapy (allergy treatment placed under the tongue) is not recommended^[15].

Managing asthma at home

You can control your asthma by knowing the warning signs of an asthma attack, staying away from things that cause an attack, and following your doctor’s advice^[8].

Your care team will explain how and when to use your medicines, how to monitor your asthma, ways to avoid triggers and reduce your symptoms, and what to do if your symptoms get worse. This will be recorded in your asthma action plan, which you’ll need to take to all your asthma appointments^[7].

Take steps to help keep your asthma under control^[19]:

Educate yourself so you can understand the purpose of your medicines and how to prevent symptoms. Learn how to recognize asthma attacks early and when to seek medical attention
Monitor your air flow. As part of your asthma action plan, your provider may show you how to track your asthma using a peak flow meter. Keep a record of your results
Write down any problems with your asthma and bring the record with you to your next care visit

You should have check-ups at least once a year to see how well your treatment is working. These will include checking that you’re using your inhalers correctly and your asthma action plan is up to date^[7].

Avoiding triggers at home: Follow these steps to avoid triggers^[19]:

Keep pets with fur out of your home or bedrooms if animal fur triggers asthma symptoms
Remove dust and mold from your house
Limit your time outdoors if allergen levels are high
Keep windows closed and avoid intense outdoor activity when air quality is low

To limit exposure to dust and mites, wash bedding regularly in hot water, replace carpeted floors with hardwood or linoleum (if possible), and encase pillows, mattresses and box springs in dust-proof covers^[23].

The ideal amount of humidity is between 30% and 50%, which can be measured with a hygrometer (similar to a thermometer) and regulated with a humidifier or dehumidifier^[23].

Possible complications

Asthma can cause severe flare-ups that don’t get better with treatment, called status asthmaticus. This can be fatal if you can’t get enough oxygen to your organs and tissues^[1].

Without treatment, asthma attacks can be fatal^[1]. Most asthma-related deaths occur in low- and lower-middle-income countries, where under-diagnosis and under-treatment is a challenge^[5].

People with under-treated asthma can suffer sleep disturbance, tiredness during the day, and poor concentration. Asthma sufferers and their families may miss school and work, with financial impact on the family and wider community^[5].