STUDY DESIGN

Design:

randomised controlled trial.

Allocation:

{concealed*}†.

Blinding:

blinded (outcome assessors, patients and healthcare providers [to dextromethorphan (DM) and honey], {data collectors, data analysts, and manuscript writers}†).*

Setting:

a university-affiliated paediatric practice in Hershey, Pennsylvania, USA.

Patients:

{108}† children 2–18 years of age (median age 5 y, range 2–17 y, 53% girls) who had cough due to an upper respiratory infection (rhinorrhoea and cough for ⩽7 days) and whose parents scored ⩾3 points (somewhat) for ⩾2 of 3 questions on a 7-point Likert scale that assessed cough and sleep difficulty (0  =  not at all to 6  =  extremely). Exclusion criteria included signs and symptoms of asthma, pneumonia, laryngotracheobronchitis, sinusitis, or allergic rhinitis; reactive airways disease; chronic lung disease; use of selective serotonin reuptake inhibitors; or use of an antihistamine or DM hydrobromide ⩽6 hours from bedtime or …