Gastroesophageal reflux disease (GERD) causes chronic cough and triggers asthma. Mechanisms of reflux-associated chronic cough include micro- and macroaspiration, laryngeal injury, and a vagally mediated reflex. An empiric trial of a proton pump inhibitor in patients without other etiologies of cough found through diagnostic testing may be an effective diagnostic strategy for GERD-associated cough. In GERD-associated asthma, there is evidence of neurogenic inflammation. Medical or surgical therapy of GERD results in asthma symptom improvement in about 70% of patients. A 3-month empiric trial of omeprazole, 20 mg daily, followed by esophageal pH testing in drug nonresponders, is the most cost-effective way of diagnosing asthma triggered by GERD.