Used in medical diagnostics to assess airway hyperresponsiveness in patients suspected of having asthma. Administered via inhalation, it induces bronchoconstriction in sensitive individuals, allowing clinicians to evaluate lung function changes through spirometry. The degree of airway narrowing helps confirm asthma diagnosis, especially when symptoms and baseline tests are inconclusive. Due to its potent effect, the test is performed under controlled conditions with immediate access to rescue medications.