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Performing a FeNO test

What is a FeNO test?

FeNO stands for fractional exhaled nitric oxide. Nitric oxide (NO) is a small molecule produced in your lungs. When your lungs are inflamed (for instance, if you have asthma), they can produce more NO. Your FeNO score will help your doctor to understand the level of inflammation in your lungs.

Is taking a FeNO test easy?

YES! Performing the test is like gently blowing bubbles in a drink. Almost everyone can do it including children from the age of four and patients with reduced lung function. The test itself takes 10 seconds for adults and 6 seconds for children if they can't manage a 10-second exhalation. The device will show your FeNO score in about a minute.

What do I need to do before a test?

You should not eat, drink, smoke or do strenuous exercise for two hours before your test. If you have, please tell your doctor as these factors can influence your FeNO score.

Using a FeNO device

Not all FeNO devices follow the same procedure for testing. Your healthcare professional will show you the correct steps for taking the test.

Ready for FeNO?

Download all the information you need to share the power of FeNO testing with your family, friends and healthcare team.

What is FeNO?

Download this for more information about FeNO testing.

Information for Doctors

Download and take this leaflet to your doctor / healthcare professional.

Taking a test

Download our handy guide on how to perform a FeNO test.

Tell your doctor about FeNO

Simply mention FeNO at your
next appointment

Download PDF to take
to your next appointment