Challenge Testing can help diagnose asthma by utilizing Methacholine which causes the airway to slightly narrow upon breathing it in. Your medical provider will get your baseline information through a breathing test before administering the Challenge Test. A small dose of Methacholine will be given to you through a mask and then your medical provider will perform a breathing test to determine if you have airway restriction. Once you begin to show symptoms of breathing distress, the test will be concluded.
American College of Allergy, Asthma, and Immunology (acaai.org)
The American Academy of Allergy, Asthma & Immunology | AAAAI