ATP and Capsaicin Cough Provocation Test in Chronic Cough and Bronchiectasis

This is a randomized, cross-over, single-blind trial. Eligible patients will be randomly assigned to undergo either capsaicin or adenosine triphosphate (ATP) cough provocation test, followed by a washout period of 2 to 14 days. Participants will be crossed-over to undergo another cough provocation test. Patient would be under observation in the out-patient clinics for \~2 hours following the cough provocation tests in case of severe adverse events.