FeNO Testing for Asthma & Airway Inflammation

What Is FeNO Testing?

FeNO stands for Fractional exhaled Nitric Oxide. FeNO testing measures the level of nitric oxide in your breath, which can be a marker of airway inflammation.

This test is often used to:

• Evaluate inflammation linked to asthma
• Help confirm asthma diagnosis in certain patients
• Guide treatment planning and medication decisions
• Monitor asthma control over time

FeNO testing is quick, safe, and performed in-office.

Why FeNO Testing Is Important for Asthma Management

Asthma is not the same for every patient. Some types of asthma involve higher levels of inflammation and understanding that inflammation can help guide the most effective care. FeNO testing can help:

• Determine whether airway inflammation is present
• Support personalized asthma medication planning
• Reduce trial-and-error treatment changes
• Monitor whether treatment is effectively controlling inflammation

It’s especially helpful for patients whose symptoms continue despite treatment or whose diagnosis is unclear.

Who Should Consider FeNO Testing?

You may benefit from FeNO testing if you:

• Have suspected asthma and need further evaluation
• Have asthma symptoms that are difficult to control
• Experience chronic cough or wheezing
• Have frequent asthma flare-ups
• Need treatment adjustments and monitoring
• Want a clearer picture of airway inflammation

FeNO testing is commonly used alongside other asthma evaluations to improve accuracy and outcomes.

What to Expect During FeNO Testing

FeNO testing is simple and non-invasive.

During the test, you can expect:

• Instructions from the clinical team on how to breathe during testing
• A controlled breath into a testing device
• A quick measurement of nitric oxide levels in your exhaled breath
• Same-visit review of results and next steps

The test is comfortable for most patients and typically takes only a few minutes to perform.