What is a FeNO Test?

• Your airway tubes can become inflamed in asthma, and this produces a chemical called nitric oxide.
• The FeNO test measures how much nitric oxide is in your breath when you breathe out and helps us understand how much inflammation you have in your lungs.
• The test may help to diagnose asthma or to see how well treatments are working.
• FeNO can be high for other reasons (e.g. hay fever) and is not high in all types of asthma.

What should I avoid prior to the test?

Several things can affect the results of the FeNO Test.

• 24 hours before - Avoid alcohol consumption
• 12 hours before - Avoid smoking
• 12 hours before - Avoid foods high in nitrates such as rocket, green beans, spinach, leek, spring onion, radish, cucumber, carrot, beetroot, Chinese cabbage, potato, turnips, garlic, cabbage, sweet pepper, green pepper.
• 6 hours before DO NOT use your preventer inhaler (containing inhaled steroid)
• 1 hour before - Avoid eating, exercise and using your inhalers. 

What happens during a FeNO test?

• You can sit down for the test and first youwill be asked to take a deep breath in with your mouth open then breathe out slowly and steadily into the mouthpiece for about 10 seconds. 
• the test is easy to do but you may need to do it more than once to get a result.
• The test usually takes less than 5 minutes to perform.