Fractional Exhaled Nitric Oxide (FENO)

A measurement to assess and monitor your asthma

Under clinic services, procedures, FeNO: Edit this page to say “FeNO stands for fractional exhaled nitric oxide. This is a simple breathing test that measures the amount of nitric oxide in your breath, which is a marker of eosinophilic inflammation in the airways. It is simple, noninvasive, and only takes a few seconds. It is useful for both adults and children. It can help better manage your asthma in a number of ways:

• Understanding whether or not your asthma might respond to a medicine called an inhaled steroid.
• Assessing whether you are compliant with your steroidal asthma medicine.
• Determining the right dose of inhaled steroid and whether the dose can be lowered safely without relapse.
• Deciding whether other medications, including biological medications, might be needed.
• Possibly preventing future asthma attacks.

If your FeNO is elevated, it may mean that you are not compliant, that your asthma is not well-controlled, or that there may be an increased risk of future asthma attacks. If your FeNO is normal, it may mean that your asthma is controlled and your dose of inhaled steroid may be able to be tapered.