Potential subjects with chronic cough of unknown origin will be identified through the above outpatient clinics. Those who meet the inclusion and exclusion criteria will be asked to join the study testing the efficacy of twice daily esomeprazole 40 mg taken for 3 months in the setting of chronic cough. Potential subjects will be consented for the study prior to leaving the enrolling clinic. A total of 40 subjects will be recruited into our study.