Are people still doing the methacholine challenge, and are there risks to it?

Methacholine test. Mostly it is done where the diagnosis of asthma is doubtful. It should be done under the careful supervisision of a physician who has experience in the bronchial challenge tests. The test can be done in the hospital pulmonary lab or in the office setting with appropriate. Staff and safety equipment to treat asthma like symptoms. The test is still being done when indicated.
Yes & depends. This test has 2 uses: measuring asthma severity & ruling out asthma. The former is used in clinical studies where to quan changes in asthma severity with treatment. Often patients with severe asthma are studied. For them this test can be dangerous. The latter is used when symptoms are subtle & asthma is one of several possible diagnoses. Here the risk of severe symptoms is quite low.
Methacholine test. At the national jewish hospital in denver we did lot of research work for the diagnosis of asthma. The test can take up to about an hour. The patient has to be monitored closely during the test. Bronchial challenge tests can also be done with histamine, mannitol and individual allergens like pollen, dust, molds etc.