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FeNo (Exhaled Nitric Oxide)
A FeNO test is a simple, non‑invasive breathing test that measures the amount of nitric oxide in your breath. A FeNO test (also called a fractional exhaled nitric oxide test or airway inflammation test) helps doctors check for inflammation inside your airways, which is common in asthma.
The FeNO test is safe, painless, and quick. You breathe out slowly into a small device, and it gives a reading that shows how irritated or inflamed your airways are. This information helps your doctor diagnose asthma, monitor your symptoms, and decide whether your treatment needs adjusting.
A FeNO test is especially useful if you have ongoing breathing symptoms, suspected asthma, or if your doctor wants to check how well your asthma medicine is working.
What happens during a FeNO test?
- Slow, steady breath: You take a deep breath in, then breathe out slowly and evenly into the FeNO device.
- One simple step: The device measures the nitric oxide level in your breath, usually shown in parts per billion (ppb).
- Quick process: The FeNO test only takes a few minutes and does not require any hard blowing or big breaths.
- Clear results: Higher FeNO levels usually mean more airway inflammation. Lower levels suggest better control.
Friendly technicians guide you through the FeNO test so the process feels calm, simple, and easy to understand.
What is a FeNO test?
A FeNO test measures nitric oxide in your breath to check for airway inflammation.
Why do I need a FeNO test?
It helps diagnose asthma, monitor inflammation, and guide treatment decisions.
Does a FeNO test hurt?
No. It is completely painless and only involves a slow, steady breath out.
What do high FeNO levels mean?
High levels usually mean your airways are inflamed, which is common in asthma.
What do low FeNO levels mean?
Low levels suggest your asthma is well controlled or that inflammation is not the main issue.
Is a FeNO test safe?
Yes. It is non‑invasive and uses no radiation.
Is a FeNO test the same as an asthma test?
A FeNO test helps diagnose and monitor asthma, but doctors often use it alongside other breathing tests.
What is the minimum age to book a FeNo test at CRS?
Children need to be aged 5 years or older.
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