Asthma Diagnosis

How will my doctor find out if I have asthma?

Talk to your doctor if you or your child has asthma symptoms. Let them know if you know of anything that puts you at risk for asthma. You may need to see a team of healthcare providers, including your doctor, an asthma specialist, or an allergy specialist (called an allergist).

Tips for talking with your healthcare provider fact sheet

Tips for Talking With Your Healthcare Provider

Get tips for talking to your healthcare provider and sample questions to ask at your next appointment.

Diagnostic tests

You may need the following tests to figure out whether your symptoms are caused by asthma.


Spirometry is a type of lung function test that measures how much air you breathe out. It also measures how fast you can blow air out. 

During the test, a technician will ask you to take a deep breath in. Then, you'll blow as hard as you can into a tube connected to a small machine. The machine is called a spirometer. Your healthcare team may have you inhale, or breathe in, medicine that helps open your airways and then blow into the tube again. They can then compare your test results before and after taking the medicine. Some people feel lightheaded or tired from the required breathing effort.

Spirometry with bronchodilator tests 

These tests measure how much and how fast air moves in and out both before and after you breathe in a medicine to relax the muscles in your airway.

Bronchoprovocation tests 

These tests measure how your airways react when you breathe in specific substances in the air. During this test, you breathe in allergens or medicines that may tighten the muscles in your airways. How fast the air moves when you breathe in and out is measured before and after the test.

Peak expiratory flow (PEF) tests 

PEF tests measure how fast you can blow air out using maximum effort. This test can be done during spirometry or with a small handheld device.

Fractional exhaled nitric oxide (FeNO) tests

Fractional exhaled nitric oxide (FeNO) tests measure how much nitric oxide is in your breath. High levels of nitric oxide may mean that the airways in your lungs are inflamed, which can make it hard to breathe. 
For this test, you will breathe out into a tube that is connected to the portable device. It requires steady but not heavy breathing and has few or no risks. It is done in adults and children age 5 and older.

What is Fractional Exhaled Nitric Oxide (FeNO) Testing?

What is Fractional Exhaled Nitric Oxide (FeNO)Testing?

This 2-page fact sheet describes how the test works and when your healthcare provider may use it.

Allergy skin or blood tests

These tests can tell your doctor which allergens, such as pet dander or pollen, cause a reaction in your body when you are around these substances. Your doctor may do these tests if you have a history of allergies.

Visit our Asthma in Children page to learn how asthma is diagnosed in children younger than 6.

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