Diagnosed by the use of a methacholine challenge test which can amplify abnormalities on spirometry thus allowing the physician to uncover signs of asthma
. Cough-variant asthma
is usually a milder form of asthma
and responds very well to traditional asthma medications.
Gastroesophageal reflux can be diagnosed by a test called a 24-hour pH probe, endoscopy, or by improvement in the cough with a trial of antireflux medications.
Other cause is post nasal drip caused by sinusitis.