Asthma Diagnosis

To diagnose asthma, your doctor will discuss your medical history with you and perform a physical exam. You may need a lung function test and maybe other tests, such as a chest or sinus X-ray. If you or your child are having problems breathing on a regular basis, don’t wait! Visit a doctor immediately. Knowing what to expect during the diagnostic process may help.

What Are Common Ways to Diagnosis Asthma?

Personal and medical history. Your doctor will ask you questions to understand your symptoms and their causes. Bring notes to help jog your memory. Be ready to answer questions about your family history, the medicines you take and your lifestyle. This includes any current physical problems. Shortness of breath, wheezing, coughing and tightness in your chest may show asthma. This also includes all previous medical conditions. A history of allergies or eczema increases your chance of asthma. A family history of asthma, allergies or eczema increases your chance of having asthma, too. Tell your doctor about any home or work exposure to environmental factors that can worsen asthma. For example, these might include pet dander, pollen, dust mites and tobacco smoke. The doctor may also ask if you get chest symptoms when you get a head cold.

Physical examination. If your doctor thinks you have asthma, they will do a physical exam. They will look at your ears, eyes, nose, throat, skin, chest and lungs. This exam may include a lung function test to detect how well you exhale air from your lungs. You may also need an X-ray of your lungs or sinuses. A physical exam then allows your doctor to review your health.

Lung function tests. To confirm asthma, your doctor may have you take one or more breathing tests known as lung function tests. These tests measure your breathing. Lung function tests are often done before and after inhaling a medication known as a bronchodilator (bron-co-DIE-a-later), which opens your airways. If your lung function improves a lot with use of a bronchodilator, you probably have asthma. Your doctor may also prescribe a trial with asthma medication to see if it helps. Common lung function tests used to diagnose asthma include:

Spirometry. This is the recommended test to confirm asthma. During this test, you breathe into a mouthpiece that’s connected to a device. It is called a spirometer. The spirometer measures the amount of air you’re able to breathe in and out and its rate of flow. You will take a deep breath and then exhale forcefully.  

Peak airflow. This test uses a peak flow meter. It's a small, handheld device that you breathe into to measure the rate at which you can force air out of your lungs. During the test you breathe in as deeply as you can and then blow into the device as hard and fast as possible. If you're diagnosed with asthma, you can use a peak flow meter at home to help track your condition.

Trigger tests. If your other results are normal, but you’ve been experiencing signs and symptoms of asthma, your doctor may use known asthma triggers to try and provoke a mild reaction. If you don’t have asthma, you won’t react. But if you do have asthma, you likely will develop asthma symptoms.

Will They Test for Other Conditions?

If your doctor thinks you have something other than asthma or besides asthma, they may run other tests. These might include a chest X-ray, acid reflux test, sinus X-rays or other specialized tests. Your doctor may also perform allergy tests. Allergy tests aren’t used to determine if you have asthma. But, if you have allergies, they may be causing your asthma.

What Are the Different Types of Asthma?

There are four levels of asthma, based on how severe it is. How often you have symptoms and your lung function determines how bad your asthma is. Your doctor will ask you questions about how often you have symptoms and wake up at night from coughing or trouble breathing. They might also ask how often you have trouble doing normal activities or use a rescue inhaler.

Intermittent Asthma — You have symptoms less than twice a week and wake up less than two nights a month.
Mild Persistent Asthma — You have symptoms two or more days a week and wake up three to four nights a month.
Moderate Persistent Asthma — You have symptoms at least every day and wake up one or more nights a week.
Severe Persistent Asthma — You have symptoms during the day and wake up every night due to asthma.

How Is Asthma Diagnosed in Children?

Diagnosing asthma in children under 5 is a little different. Children this age usually are not given a breathing test. Instead, the doctor asks about certain signs and symptoms and prescribes a bronchodilator if they think it might be asthma. If the bronchodilator helps reduce your child’s symptoms, that is a sign that your child may have asthma.

Medical Review September 2015.