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Asthma is a chronic, inflammatory disease of the lungs in which the airways become sensitive to allergens (any substance that triggers an allergic reaction) and irritants (irritating things in the air). Several things happen to the airways when a person is exposed to certain triggers:
The lining of the airways becomes swollen and inflamed.
The muscles that surround the airways tighten.
The production of mucus is increased, leading to mucus plugs.
All of these factors will cause the airways to narrow, thus making it difficult for air to go in and out of your lungs, causing the symptoms of asthma.
Asthma may resemble other respiratory problems, such as emphysema, bronchitis, and lower respiratory infections. It is often underdiagnosed and many people with the disease do not know they have it. Sometimes, the only symptom is a chronic cough, especially at night, or coughing or wheezing that occurs only with exercise. Some people think they have recurrent bronchitis, since respiratory infections usually settle in the chest in a person predisposed to asthma.
The exact cause of asthma is not completely known. It is believed to be partially inherited, but it also involves many other environmental, infectious, and chemical factors. After a person is exposed to a certain trigger, the body releases histamine and other agents that can cause inflammation in the airways. The body also releases other factors that can cause the muscles of the airways to tighten or become smaller. There is also an increase in mucus production that may clog the airways.
Some people have exercise-induced asthma, which is caused by varying degrees of exercise. Symptoms can occur during, or shortly after, exercise. In some people, stress or strong emotions can trigger an asthma attack. Each person has different triggers that cause the asthma to worsen. You should discuss this with your doctor.
The changes that occur in asthma are believed to happen in two phases:
An immediate response to the trigger leads to swelling and narrowing of the airways. This makes it initially difficult to breathe.
A later response, which can happen four to eight hours after the initial exposure to the allergen, leads to further inflammation of the airways and obstruction of airflow.
Although anyone may have an asthma attack, it most commonly occurs in the following people:
Children and adolescents ages 5 to17
People living in urban communities
Other factors include the following:
Family history of asthma
Personal medical history of allergies
Children most susceptible to asthma attacks include the following:
Children with a family history of asthma
Children who have allergies
Children who have exposure to secondhand tobacco smoke
People with asthma have acute episodes when the air passages in their lungs become narrower, and breathing becomes more difficult. These problems are caused by an oversensitivity of the lungs and airways:
The lungs and airways overreact to certain triggers causing:
The lining of the airways to become inflamed and swollen.
Tightening of the muscles that surround the airways.
An increased production of mucus.
Breathing becomes harder and may hurt.
Talking and sleeping may be difficult.
There may be coughing sometimes with mucus.
There may be a wheezing or whistling sound, which is typical of asthma. Wheezing occurs because of the rush of air that moves through the narrowed airways.
To diagnose asthma and distinguish it from other lung disorders, doctors rely on a combination of medical history, physical examination, and laboratory tests, which may include the following:
Spirometry. A spirometer is a device used by your doctor that assesses lung function. Spirometry is the evaluation of lung function with a spirometer. The test is performed by blowing as hard as possible into a tube connected to a small machine (a spirometer) that measures the amount of air breathed out and in as well as the speed it is breathed out. This is one of the simplest, most common pulmonary function tests and may be necessary for any or all of the following reasons:
To determine how well the lungs receive, hold, and utilize air
To monitor a lung disease
To monitor the effectiveness of treatment
To determine the severity of a lung disease
To determine whether the lung disease is restrictive (decreased airflow) or obstructive (disruption of airflow)
Peak flow monitoring (PFM). A device used to measure the fastest speed in which a person can blow air out of the lungs. To use a peak flow meter, a person takes a deep breath in and then blows as hard and fast as possible into a mouthpiece. During an asthma or other respiratory flare-up, the airways in the lungs slowly begin to narrow. This will slow the speed of air leaving the lungs and can be measured by a PFM. This measurement is very important in evaluating how well or how poorly the disease is being controlled.
Chest X-rays. A diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.
Blood tests. These tests are done to analyze the amount of carbon dioxide and oxygen in the blood.
According to the CDC, the American Academy of Allergy, Asthma, and Immunology, and other organizations, triggers for asthma include the following:
Respiratory infections and sinusitis
Animal protein (dander, urine, oil from skin)
House dust or dust mites
Infections can cause irritation of the airways, nose, throat, lungs, and sinuses, and worsens asthma.
Sensitivity to medications
Strong odors and sprays, such as perfumes, household cleaners, cooking fumes, paints, and varnishes
Chemicals, such as coal, chalk dust, or talcum powder
Air pollutants, such as tobacco smoke, wood smoke, chemicals in the air and ozone
Changing weather conditions, including changes in temperature, barometric pressure, humidity, and strong winds
Chemical exposure on the job, such as occupational vapors, dust, gases, or fumes.
Medications, such as aspirin and additives, such as sulfites, cause up to 20 percent of adult asthmatic attacks as a result of sensitivities or allergies to them. These medications often include:
Other nonsteroidal anti-inflammatory medications, such as ibuprofen, indomethacin, naproxen
Sulfites used as preservatives in food and beverage
Before taking any medication, including over-the-counter medications, consult your doctor.
Strenuous physical exercise can trigger an asthma attack often because of the inhaled cool and dry air. Long-term strenuous activities, such as long-distance running, are most likely to induce asthma, and swimming is the least likely.
GERD, a condition characterized by persistent reflux of stomach acids, is common in individuals with asthma. Symptoms may include heartburn, belching, or spitting up in infants.
Emotional anxiety and nervous stress
Tobacco smoke, whether directly or passively inhaled, has been shown to worsen asthma.
Wood smoke from wood-burning heating stoves and fireplaces can release irritating chemicals, such as sulfur dioxide.
Reactions from stress and anxiety are considered to be more of an effect than a cause. They can cause fatigue, which may affect the immune system and, in turn, increase either asthma symptoms or bring on an attack.