Cochrane review: Over‐the‐counter medications for acute cough in children and adults in ambulatory settings
Authors: Smith Susan M , Schroeder Knut , Fahey Tom 
Published: March 2009

Background

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.

Objectives

To assess the effects of oral OTC cough preparations for acute cough.

Search strategy

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).

Selection criteria

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.

Data collection and analysis

Two review authors independently screened potentially relevant citations and independently extracted data and assessed study quality. Quantitative analysis was performed where appropriate.

Main results

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.

Authors' conclusions

There is no good evidence for or against the effectiveness of OTC medicines in acute cough. The results of this review have to be interpreted with caution due to differences in study characteristics and quality. Studies often showed conflicting results with uncertainty regarding clinical relevance. Higher quality evidence is needed to determine the effectiveness of self‐care treatments for acute cough.

Plain language summary

The evidence for effectiveness of oral over‐the‐counter cough medicines is weak

Acute cough is a common and troublesome symptom in people who suffer from acute upper respiratory tract infection (URTI). Many people self‐prescribe over‐the‐counter (OTC) cough preparations and health practitioners often recommend their use for the initial treatment of cough. The results of this review suggest that there is no good evidence for or against the effectiveness of OTC medications in acute cough. The results of this review have to be interpreted with caution because the number of studies in each category of cough preparations was small. Many studies were of low quality and very different from each other, making evaluation of overall efficacy difficult.