Methacholine challenge testing is a better predictor of not having asthma than of having asthma.

As I tell my patients when I am testing them, at this stage (Methacholine challenge) we are essentially trying to prove that you don’t have reactive airways. Why? So that you don’t spend your life on medications that are of no benefit to your health. So that your physician can better pursue the source of your distress and ultimately provide better management of your health.

You need to have spirometry performed at a real Pulmonary Function Laboratory (not in a doctor’s office) to rule out obstructed airflow. You need to perform the spirometry both before and after using a bronchodilator (this is all done in the lab). If the results are normal and asthma is a suspicion, then your next step is the Methacholine challenge.

You must follow pre-test instructions carefully in order to obtain accurate results. Your spirometry and your methacholine challenge need to be performed on different days.

Good luck and ask for a pulmonary consult if you need one.