Experimentally induced cough.

The experimental induction of cough has become an important component of clinical cough research. Measurement of cough reflex sensitivity allows the evaluation of the effect of pharmacological and other interventions on the cough reflex, as well as the performance of epidemiological studies relevant to cough. The most commonly used tussive agents include capsaicin, citric acid and ultrasonically nebulized distilled water (fog). Methodological considerations are vital to the performance of high quality, reproducible cough challenge, which is especially important when measuring the effect of an experimental intervention on cough reflex sensitivity. For the optimal execution of clinical trials employing inhalation cough challenge, the subject population must be carefully selected, and the usefulness and potential limitations of data obtained from cough challenge studies need to be appreciated.