#1 FeNO Testing in NYC
FeNO Testing
A simple, non-invasive breath test that measures airway inflammation—helping diagnose asthma, monitor treatment effectiveness, and determine the best medication approach for your condition.
- Under 5 minutes
- Covered by insurance
- Immediate results
What is FeNO Testing?
FeNO stands for Fractional Exhaled Nitric Oxide. It is a quick, non-invasive breath test that measures the amount of nitric oxide gas in your exhaled breath. Nitric oxide is a biomarker of inflammation in the airways—when your airways are inflamed, your body produces higher levels of this gas.
The test is performed using a portable handheld device. You simply breathe in deeply, then exhale steadily into the mouthpiece for several seconds while the device measures the nitric oxide concentration in your breath. The entire test takes less than five minutes and requires no needles, no allergen exposure, and no discomfort.
FeNO testing is primarily used to diagnose asthma and to determine whether asthma is driven by Type 2 inflammation—the kind that typically responds well to inhaled corticosteroids. It can also monitor how effectively your asthma medications are controlling airway inflammation and help predict the risk of asthma exacerbations.
This test is suitable for adults and children aged 5 and older. Results are available immediately, allowing your allergist to make informed treatment decisions during your appointment.
FeNO Result Levels (PPB)
Normal / Low
Intermediate
High / Elevated
What to Expect with FeNO Testing
Book an appointment
Schedule a visit at one of our 10 convenient NYC locations. Your allergist will determine whether FeNO testing is appropriate based on your symptoms, medical history, and current medications. The test is often recommended alongside spirometry to get a complete picture of your lung health.
Complete the Test
Review Results & Treatment
Common Uses for FeNO Testing
FeNO testing provides valuable insights for both diagnosing asthma and optimizing ongoing asthma management.
Diagnosing Asthma
Helps confirm asthma diagnosis by measuring airway inflammation, especially when combined with spirometry and clinical symptoms.
Identifying Type 2 Inflammation
Determines whether asthma is driven by Type 2 (eosinophilic) inflammation, which typically responds well to inhaled corticosteroid therapy.
Monitoring Treatment Response
Tracks how well inhaled corticosteroids are controlling airway inflammation. Lower FeNO after starting treatment indicates the medication is working.
Assessing Medication Adherence
Persistently high FeNO levels in patients on inhaled corticosteroids may indicate poor medication adherence or need for treatment adjustment.
Predicting Asthma Exacerbations
High FeNO levels are associated with increased risk of asthma attacks, helping identify patients who need more aggressive treatment.
Guiding Biologic Therapy Decisions
Helps allergists determine whether patients with severe asthma are candidates for biologic medications targeting Type 2 inflammation.
Evaluating Allergic Asthma
FeNO levels tend to be higher in patients with allergic asthma and can help distinguish it from other types of asthma.
Supporting Medication Tapering
When asthma is well-controlled and FeNO remains low, it may support decisions to safely reduce corticosteroid doses under medical supervision.
Advantages of FeNO Testing
Fast, Simple & Non-Invasive
Immediate, Objective Results
Identifies Steroid-Responsive Inflammation
Monitors Treatment Without Medication Interruption
Complements Other Asthma Tests
Helps Prevent Asthma Attacks
How to Prepare for FeNO Testing
FeNO testing requires minimal preparation. The following simple guidelines will help ensure accurate results:
- Avoid eating or drinking (except water) for at least 1 hour before your test. Food and beverages can temporarily affect nitric oxide levels.
- Do not smoke for at least 1 hour before testing. Smoking suppresses nitric oxide levels and can lead to inaccurate results. If you are a regular smoker, inform your provider.
- Continue taking your asthma medications as prescribed unless your allergist specifically instructs otherwise. FeNO testing can be performed while you are on treatment.
- Avoid vigorous exercise for at least 1 hour before the test, as intense physical activity can temporarily alter nitric oxide levels.
- Inform your provider if you have a respiratory infection or have recently had one, as this can temporarily elevate FeNO levels.
FeNO Testing Frequently Asked Questions
Is FeNO testing painful or uncomfortable?
No, FeNO testing is completely painless and non-invasive. The test simply involves breathing out steadily into a handheld device for about 10 seconds. Most patients find it very easy to perform and experience no discomfort.
How long does a FeNO test take?
A FeNO test takes less than five minutes from start to finish. The actual exhalation measurement takes only about 10 seconds, but the test is typically repeated to ensure consistent, accurate results. Your allergist will review the results with you immediately.
Can children undergo FeNO testing?
Yes, FeNO testing is suitable for children aged 5 and older. The test is simple enough for most school-aged children to perform successfully with basic instruction and guidance from a trained technician.
What do high FeNO levels mean?
High FeNO levels (typically above 50 ppb in adults) indicate significant airway inflammation, which strongly suggests asthma with Type 2 inflammation. This type of inflammation usually responds well to inhaled corticosteroid medications. Your allergist will interpret your results in the context of your symptoms and medical history.
What if my FeNO results are normal but I still have asthma symptoms?
FeNO measures Type 2 airway inflammation, but not all asthma is driven by this type of inflammation. Low FeNO does not rule out asthma—it may indicate non-eosinophilic asthma or that your inflammation is already well-controlled by medications. Your allergist will use FeNO alongside other tests like spirometry and your clinical symptoms to reach an accurate diagnosis.
Do I need to stop my asthma medications before a FeNO test?
No, in most cases you should continue taking your asthma medications as prescribed. One of the advantages of FeNO testing is that it can be performed while you are on treatment, making it ideal for monitoring how well your medications are controlling inflammation. Always follow your allergist’s specific instructions regarding your medications.
How is FeNO testing different from spirometry?
FeNO measures airway inflammation by detecting nitric oxide in your breath. Spirometry measures lung function—specifically how much air you can breathe in and out and how quickly. The two tests provide complementary information. FeNO tells your allergist about inflammation, while spirometry tells them about airflow obstruction. Both are valuable for diagnosing and managing asthma.
Can conditions other than asthma cause high FeNO levels?
Yes, other conditions can elevate FeNO levels, including allergic rhinitis, eosinophilic bronchitis, and certain respiratory infections. Your allergist will consider your complete clinical picture—including symptoms, medical history, and other test results—when interpreting your FeNO levels.
How often will I need FeNO testing?
The frequency of FeNO testing depends on your asthma severity and treatment plan. For newly diagnosed asthma, your allergist may repeat FeNO testing after starting inhaled corticosteroids to confirm the medication is reducing inflammation. For ongoing monitoring, testing may be done at regular intervals or when asthma symptoms change. Your provider will determine the appropriate schedule for your situation.
Is FeNO testing covered by insurance?
Yes, FeNO testing is typically covered by most insurance plans when performed for the diagnosis or management of asthma. Our office will verify your coverage before your appointment and help you understand any out-of-pocket costs.