How is asthma diagnosed?
There is no single test for asthma. Doctors make the diagnosis of asthma when a person has breathing symptoms typical of asthma that come and go, and there is also evidence that sometimes air does not flow in and out of their lungs normally.
Airflow can vary in healthy people too (e.g. when someone has a cold their lungs may not work as well as usual). But people with asthma have a much bigger difference than healthy people between how their lungs work at their best and at their worst.
How well the lungs work (lung function) is tested using a spirometer machine. You blow into a tube as forcefully as you can for a few seconds. The spirometer measures the amount of air pushed through the tube, as well as lung capacity and other measurements. Most children over 6 years old can do this asthma test, but is not used for preschool children or adults with certain medical conditions.
- Find out how asthma is diagnosed in children.
- Find out how asthma is diagnosed in adults and adolescents.