What happens during the test?

You will be breathing a small amount of methacholine, which can cause some airway irritation in asthmatics. Following this, you will be taking a deep breath of regular air and blowing the air out hard through a mouthpiece. We will measure the exhaled flow to see if the methacholine has decreased your ability to blow air out fast. Typically, in asthmatics, methacholine inhalation will decrease peak expiratory flow. At the end, we give you a bronchodilator to reverse the effect of the methacholine. 

Will it hurt? 

No. You may get "light headed" from the deep breathing or get some discomfort if the methacholine irritates your airways and causes wheezing but there is no painful procedure involved in a Methacholine Challenge.

What do I do to prepare?

Do not take any of your bronchodilators for two hours prior to the test unless you feel that you need to.  Do not eat a large meal just before the test.

How long will it take?

Less than one hour.

What is the reason for the test?

A Methacholine Challenge is used to diagnose or to rule out asthma for a person that is having signs and symptoms of asthma.

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