Allergist

Fractional Exhaled Nitric Oxide Test

Breathing test that helps assess airway inflammation often associated with asthma.

What is a Fractional Exhaled Nitric Oxide Test?

A fractional exhaled nitric oxide test, often called FeNO testing, measures nitric oxide in the breath. This can help assess airway inflammation that is often associated with certain types of asthma.

This procedure helps to:

Measure airway inflammation
Support asthma evaluation
Help assess allergic or eosinophilic airway activity
Monitor response to asthma treatment in selected patients
Add objective information to breathing symptom assessment

What to expect after a Fractional Exhaled Nitric Oxide Test?

The test is simple and noninvasive. You breathe steadily into a device that measures nitric oxide in the exhaled air, and results are typically available quickly.

You will breathe into a testing device
The test is noninvasive and usually brief
No needles or sedation are required
Results are often available quickly
Normal activities can resume right away

Why is it performed?

• To support the diagnosis of asthma
• To assess airway inflammation
• To help guide inhaled steroid treatment in selected patients
• To monitor ongoing respiratory care
• To add information beyond standard symptom review

Risks and Considerations

• The test is generally very low risk
• Good breathing technique is needed for accurate results
• Results must be interpreted with the clinical picture
• Additional lung testing may still be needed
• Not every type of asthma shows the same pattern

Early detection is important for managing the condition and preventing further complications.

Schedule a consultation today.

FAQs

Is the FeNO test painful?

No. It is a simple breathing test and is not painful.

How long does it take?

It is usually completed quickly during the visit.

Does this replace spirometry?

No. It gives different information and may be used alongside spirometry and clinical evaluation.

Do I need to prepare for the test?

Follow any instructions from your provider, since certain factors may affect results.

When should I call my doctor?

Call your provider if breathing symptoms worsen or if you have questions about what the results mean.

Allergist

Doral Health & Wellness Allergist Department

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