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Asthma is a chronic lung condition that causes periodic or persistent breathing problems. It is caused by airway inflammation. Asthma is diagnosed by taking a medical history and conducting various lung function tests.
A person may start on the path to an asthma diagnosis because they are experiencing general symptoms associated with asthma. These symptoms include:
Learn more about symptoms of asthma.
Asthma typically begins in childhood, but it can also develop in adulthood. Asthma is fairly common in the United States. Nearly 25 million Americans had asthma in 2018, including approximately 5.5 million children, according to the Centers for Disease Control and Prevention. Globally, approximately 339 million people have asthma.
In the United States, more women than men have asthma — 12.6 million women compared to 6.7 million men. However, among children, more boys than girls have asthma — 3.1 million compared to 2.4 million.
Race, ethnicity, and socioeconomic status influence the diagnosis and management of asthma in the U.S. Compared to white Americans, Black Americans are 1.5 times as likely to have asthma, and Puerto Rican Americans are twice as likely to have asthma. Black Americans are five times as likely to visit the emergency room for asthma.
The Asthma and Allergy Foundation of America has identified several factors that contribute to racial, ethnic, and economic disparities in asthma health outcomes, including lack of access to health care and exposure to air pollution.
Read more about causes of asthma.
Many people start the asthma diagnosis journey with their primary care provider or with their pediatrician during childhood. An official diagnosis may require seeing specialists, such as a pulmonologist (lung specialist) or an allergist.
A definitive asthma diagnosis requires the presence of respiratory symptoms consistent with asthma and test results demonstrating variable airflow obstruction. This means there are limits to your breathing capacity that vary based on asthma triggers.
Talking to your doctor or your child’s pediatrician is the first step to diagnosing asthma. Your doctor will ask you questions about your symptoms, your medical history, family medical history, and any risk factors for asthma.
After taking a medical history, your health care provider may examine your nose, throat, and ears and listen to your breathing. They may also examine your skin for eczema or symptoms of an allergic reaction.
Pulmonary function, or lung function, tests help diagnose asthma and other respiratory diseases. The tests below are commonly used to diagnose asthma.
Spirometry is the primary test used to diagnose asthma in adults and children over the age of 5. This test assesses airway obstruction. The test is performed by breathing into a tube attached to a spirometer to measure how much air you can exhale and how quickly you can exhale. The test is then performed again after inhaling a fast-acting bronchodilator. A bronchodilator is a medication that expands the airways.
An exhaled nitric oxide test detects inflammation in the airways. High levels of nitric oxide, a gas produced by the lungs, can indicate the airways are inflamed — a potential sign of asthma. The test is performed by breathing into a machine that measures nitric oxide levels.
Challenge tests may be used when spirometry tests don’t show definitive results. They are often performed by an asthma specialist to ensure safety. A challenge test is performed by triggering asthma symptoms. This can be done by administering a substance that causes symptoms or performing physical activity to trigger symptoms. Lung function tests are performed before and after asthma symptoms are triggered.
You will always be given medication to stop symptoms once the challenge is complete. Safety is an important consideration when performing challenge tests. You will not be given a challenge test if you have health conditions that make it unsafe, such as uncontrolled high blood pressure or a recent heart attack or stroke, or if you are pregnant.
Pulmonary function tests used to diagnose asthma are difficult to perform in children age 5 and under. For young children, doctors generally rely on parental reports of symptoms. Keeping detailed notes of your child’s symptoms in advance of an appointment can help you discuss your concerns with their pediatrician. Asking other caregivers to take notes of breathing difficulties may also be beneficial.
Depending on the severity of a child’s symptoms, a doctor may prescribe an asthma treatment like an inhaler to see how a child responds. A doctor may also recommend allergy testing if asthma symptoms seem to be linked to allergic reactions.
There are several different types of asthma. You may receive a diagnosis based on the severity of your asthma:
You may also be given a diagnosis based on what causes your asthma, including:
Learn more about the types of asthma.
After being diagnosed with asthma, your doctor will help you determine the best ways to treat your asthma. Possible treatments include inhaled corticosteroids or oral medications. Parents of a newly diagnosed child may wish to develop an action plan in the event of an asthma attack or exacerbation.
Ruling out other conditions is important for an accurate diagnosis because many symptoms of asthma can be caused by other health problems. Your doctor may consider the possibility of the following health conditions when diagnosing asthma:
A doctor may order blood tests, allergy tests, or computerized tomography (CT) scans of the chest or sinuses to rule out other conditions.
Learn more about conditions related to asthma.