Chronic cough and gastro-oesophageal reflux: a double-blind placebo-controlled study with omeprazole.

Gastro-oesophageal reflux (GOR) is an important cause of chronic cough. There has been a lack of placebo-controlled trials treating GOR related chronic cough with antireflux therapy. The aim of this study was to determine the efficacy of omeprazole on GOR related chronic cough. After excluding other common causes of cough, oesophageal pH monitoring was performed on 48 patients with chronic cough. Twenty-nine patients found to have GOR were randomized in a double-blind fashion to receive omeprazole 40 mg o.d. or placebo for 8 weeks. After a 2-week washout period, patients were crossed over to the other treatment. Symptoms were recorded daily in a diary. Twenty-one patients completed both treatment periods. Cough (p=0.02) and gastric symptoms (p=0.003) improved significantly during the omeprazole treatment in twelve patients who received placebo during the first and omeprazole during the second 8-week period. In nine patients who received omeprazole during the first 8-week period, amelioration in cough reached statistical significance only after cessation of omeprazole. Gastric symptoms also remained minor during placebo in these nine patients. Omeprazole 40 mg o.d. seems to improve chronic cough in patients with gastrooesophageal reflux and the effect of omeprazole in ameliorating both cough and reflux symptoms continues after treatment ceases.