Acute cough due to upper respiratory tract infection (URTI) is a common symptom. Non-prescription over-the-counter (OTC) medicines are frequently recommended as a first-line treatment, but there is little evidence as to whether these drugs are effective.
To assess the effects of oral OTC cough preparations for acute cough.
We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2006, Issue 4); MEDLINE (January 1966 to January Week 1, 2007); EMBASE (January 1974 to January 2007); and the UK Department of Health National Research Register (June 2007).
Randomised controlled trials (RCTs) comparing oral OTC cough preparations with placebo in children and adults suffering from acute cough in ambulatory settings. We considered all cough outcomes and second outcomes of interest were adverse effects.
Two review authors independently screened potentially relevant citations and independently extracted data and assessed study quality. Quantitative analysis was performed where appropriate.
Twenty five trials (17 in adults, 8 in children) involving 3492 people (2876 adults and 616 children) were included. RESULTS OF STUDIES IN ADULTS: Six trials compared antitussives with placebo and had variable results. Two trials compared the expectorant, guaifenesin with placebo, one indicated significant benefit whereas the other did not. One trial found that a mucolytic reduced cough frequency and symptom scores. Two studies examined antihistamine-decongestant combinations and found conflicting results. Three studies compared other combinations of drugs with placebo and indicated some benefit in reducing cough symptoms. Three trials found antihistamines were no more effective than placebo in relieving cough symptoms. RESULTS OF STUDIES IN CHILDREN: Antitussives (two studies), antihistamines (two studies), antihistamine decongestants (two studies) and antitussive/bronchodilator combinations (one study) were no more effective than placebo. No studies using expectorants met our inclusion criteria. The results of one trial favoured active treatment with mucolytics over placebo. One trial tested two paediatric cough syrups and both preparations showed a 'satisfactory response' in 46% and 56% of children compared to 21% of children in the placebo group.