Nasal nitric oxide test

Inside the nose and sinuses there are tiny hairs called cilia. The cilia beat back and forth to catch dust particles and remove mucus. In some people, these cilia may not work properly, which will lead to respiratory symptoms such as coughing or difficulty breathing. The nasal nitric oxide test is used to assess if the cilia are working properly. During the test we will measure the nitric oxide (NO) level in your child’s nose.

This page from Great Ormond Street Hospital (GOSH) describes what to expect when your child has a nasal nitric oxide (nNO) test.

Do I need to bring anything?

You should receive a letter with the instructions on where to come for the test. No other preparation is needed for the test.

What does a nasal nitric oxide (nNO) test involve?

The physiologist will explain this test in more detail and be able to answer any questions you (or your child) may have before the test starts. We will ask for your permission (consent) to perform the test.

Before we start the test, we will ask your child to blow their nose if it is blocked or they have a runny nose.  The physiologists will then place a nasal olive in one nostril. The nasal olive is a long clear tube that has a spongy end that will sit inside your child’s nostril.

Once the nasal olive is placed inside your child’s nostril, the test will start. Your child will be asked to breathe in through a mouthpiece as deeply as possible. They will then be asked to breathe out at a steady pace for 10 seconds. An animation on the screen will help them achieve the correct speed. While they are breathing in and out, the nasal olive measures the nitric oxide levels in your child’s nose.

This process is repeated a few times in each nostril.


The person bringing your child for the test should have ‘Parental Responsibility’ for them. Parental Responsibility refers to the individual who has legal rights, responsibilities, duties, power and authority to make decisions for a child. If the person bringing your child does not have Parental Responsibility, we may have to cancel the test.

Are there any risks?

There are no direct risks associated with performing the test. The nasal olive will need to achieve a tight fit inside the nostril so may be uncomfortable.

Getting the results

The results for you test will be uploaded onto our electronic patient record system for your doctor to view. If you are seeing your doctor in clinic or later that day, they will go through the results of this test. If you are not seeing the doctor on the same day they will still be able to view the results ready for your next appointment. They will contact you if there is anything that your child needs to do anything before their next appointment.

Compiled by:
The Lung Function Unit in collaboration with the Child and Family Information Group
Last review date:
November 2022