Methacholine challenge test

The methacholine challenge test is a technique use in the testing and treatment of asthma. It mimics the effects of histamine in triggering asthma attacks, while at the same time breaking down quite quickly in the body and therefore presenting no long-term danger.

The test typically takes the form of an increasing dosage of inhaled methacholine, doubled at each test run. Shortly after inhalation lung function is measured, and the test is considered "positive" after a 20% reduction in lung function is noted.