Methacholine Challenge Test

What is a Methacholine Challenge Test?

The purpose of the inhaled bronchial challenge test using methacholine is to determine how responsive (or irritable) your airways are and to determine the severity of any asthma.
You will be asked to inhale a mist that contains different concentrations of methacholine. The mist is produced by a device called a nebulizer and you inhale the mist through a mouthpiece. Before the test begins and after each period of inhalation, you will be asked to blow forcefully into a spirometer.
Please feel free to ask any questions or raise any concerns at any time regarding this test with either your Doctor or the Respiratory Therapist in attendance.


Avoid the following for the recommended times before your test:

  • Smoking - 8 hours
  • Ventolin, Bricanyl, Berotec - 8 hours
  • Atrovent, Combivent - 12 hours
  • Theophylline - 24 hours
  • Slow Release Theophylline - 48 hours
  • Symbicort, Serevent, Advair, Oxeze - 48 hours
  • Accolade, Singulair, Spiriva - At least 24 hours
  • Flovent, Pulmicort, Flonase - 12 hours
  • Nasonex, Nasocort -
  • Antihistamines - 4 days
  • Beta Blockers (heart medication) - Call Us
  • Prostigmine, Neostigmine, Mestinon - Call Us

* Please note: If you experience symptoms which require you to take your medications, take them as ordered and seek medical attention if necessary.
If you are unsure if you are taking any of the above medications, check with your Pharmacists or Doctor. You may take these medications as ordered by your Doctor after your test has been completed.
Dress comfortably in loose fitting clothing.
Avoid large meals 2 to 3 hours prior to the test.

Discomforts And Risks

The inhalation of aerosols may be associated with mild shortness of breath, cough, chest tightness, wheezing, chest soreness or headache. Many patients do not have any symptoms at all. Symptoms (if they occur) are mild, last only a few minutes, and disappear following the inhalation of a bronchodilator medication, which we will give to you. The test is carried out in such a way that the danger of a severe asthmatic reaction is minimized; however, there is still a very small possibility of severe narrowing of your airways. If this occurs, you will be immediately treated.