RT Journal Article SR Electronic T1 Long-term low-dose erythromycin in patients with unexplained chronic cough: a double-blind placebo controlled trial JF Thorax JO Thorax FD BMJ Publishing Group Ltd and British Thoracic Society SP thx.2010.142711 DO 10.1136/thx.2010.142711 A1 Nadia Yousaf A1 William Monteiro A1 Debbie Parker A1 Sergio Matos A1 Surinder Birring A1 Ian D Pavord YR 2010 UL http://thorax.bmj.com/content/early/2010/10/21/thx.2010.142711.abstract AB Aims Unexplained chronic cough is a common condition with no satisfactory treatments. Previous work has suggested that cough may be linked to neutrophilic airway inflammation. This study tested the hypothesis that long-term low-dose erythromycin reduces the induced sputum neutrophil count and 24 h cough frequency in patients with unexplained chronic cough.Methods 30 patients with an unexplained chronic cough lasting more than 8 weeks were randomly assigned to take 250 mg erythromycin once daily (n=15) or placebo (n=15) for 12 weeks in a double-blind parallel group study. Cough frequency, cough reflex sensitivity and cough severity were assessed at baseline, 6, 12 and 24 weeks. The primary outcome measure was change in 24 h cough frequency at 12 weeks.Results There was no difference in the change in cough frequency between the erythromycin and placebo groups at 12 weeks (mean difference in fold change 1.1; 95% CI 0.7 to 1.5; p=0.585) or at other times. There was a statistically significant between-treatment difference in the change in sputum neutrophils at 12 weeks (−10.2% vs +6.6% with erythromycin and placebo; mean difference 16.8%; 95% CI 1.6 to 32.1; p=0.03) but not at other times. There was no difference in the change in other measures of cough between treatments.Conclusions Treatment with low-dose erythromycin for 12 weeks reduces the induced sputum neutrophil count but not cough frequency or severity in patients with unexplained chronic cough.