Persistent cough following upper respiratory tract infection (URTI) is a common problem in the clinical practice, namely post-infectious cough. The potential mechanisms are viral-induced airway epithelial damage that leads to 1) airway hyperresponsiveness and airway narrowing, 2) increase in vascular permeability resulting in airway edema, and 3) activation of inflammatory mediators from inflammatory cells resulting in airway smooth muscle contraction. It is usually spontaneously resolved, although various therapeutic trials have been used with unpredictable results. Regarding to bronchodilators, inhaled ipratropium was effective in reducing cough symptom in a small study (N=14). We conduct a double-blind randomized placebo-controlled trial to investigate the effectiveness of oral procaterol, as a bronchodilator, in non-asthmatic adult patients suffering from persistent cough post URTI.