Fractional exhaled Nitric Oxide (FeNO) is a simple, non-invasive test that measures inflammation in your airways. Elevated nitric oxide levels can be an indicator of airway inflammation, which is commonly associated with asthma and other inflammatory lung conditions.
By identifying inflammation early—or tracking how it changes over time—this test helps your care team tailor treatment more precisely, reduce the risk of flare-ups, and support more comfortable, confident breathing in daily life.
Cost
FeNO testing requires single-use supplies. A $50 fee is charged to cover the cost of these supplies.
Why it's Ordered
FeNO testing may be helpful for people who are experiencing ongoing breathing symptoms, especially when asthma is being considered. Your doctor may request FeNO testing if you:
• Have a chronic cough that doesn’t seem to go away
• Wheeze or feel chest tightness
• Feel short of breath with activity
• Have symptoms that come and go (or are worse at certain times of year)
• Have suspected asthma, or asthma that is difficult to control
• Are starting, changing, or monitoring asthma medications
Want a clearer picture of whether airway inflammation may be contributing to symptoms
Even if your breathing tests are normal, FeNO can sometimes provide additional information that helps guide your care.
What to Expect
During the test, you will be guided to:
• Take a deep breath in
• Slowly breathe out into a mouthpiece for a short period of time
Our team will coach you step-by-step. The test is painless and only takes a few minutes.
Why It's Helpful
FeNO testing gives your healthcare team helpful information about what may be happening inside your airways.
For some people, breathing symptoms like coughing, wheezing, or shortness of breath can be caused by airway inflammation. FeNO helps measure this inflammation in a quick and simple way.
FeNO is often used alongside other breathing tests (such as spirometry) to give a more complete picture of your lung health.
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How to Prepare
To help ensure your results are as accurate as possible, please follow these instructions:
- Do not eat or drink (except water) for 1 hour before the test
- Avoid leafy greens, beets, and cured meats for 12 hours before the test (these can affect results)
- Do not smoke, vape, or use nicotine products for 1 hour before the test
- Avoid hard exercise for 1 hour before the test (running, cycling, heavy lifting, etc.)
- Continue taking your regular medications unless your doctor tells you otherwise
- Bring a list of your current medications (inhalers, tablets, injections, etc.)
If you have questions about how to prepare, please don’t hesitate to contact our clinic — we’re happy to help. Our team will guide you through each step and ensure you feel comfortable and supported throughout your visit.
FAQ
Yes. FeNO testing is very safe. It is non-invasive, does not involve needles, and does not hurt. You are simply breathing into a mouthpiece.
FeNO measures a type of inflammation in the airways that is often seen in asthma and other inflammatory breathing conditions. It helps your healthcare provider understand what may be contributing to your symptoms.
FeNO is not a diagnosis on its own, but it can be a helpful piece of information. Your doctor may use FeNO along with your symptoms, spirometry, and medical history to guide diagnosis and treatment.
Certain foods, smoking, vaping, and exercise can temporarily affect FeNO results. Following the instructions helps ensure your test results are as accurate and useful as possible.
Most patients should continue their regular medications. Only stop medications if your doctor has specifically instructed you to do so. If you are unsure, please contact our clinic before your appointment.
The test itself only takes a few minutes. Your full appointment time may be slightly longer depending on whether you are having other lung function testing done the same day.
Your results are reviewed as part of your overall assessment. A report is then sent to your referring doctor, who will discuss the results and next steps with you.
FeNO testing requires single-use supplies. The $40 fee helps cover the cost of these supplies.
That’s completely normal. Most people find FeNO testing much easier than they expected. Our staff will explain everything clearly and guide you through it step-by-step