Acute cough is a common and troublesome symptom in children and adults suffering 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. There is substantial variation between countries in the availability and guidelines for use of many of these preparations.
We identified a broad range of studies of different types of preparations used at different dosages in both adults and children.
The evidence is current up to March 2014. We found no good evidence for or against the effectiveness of OTC medications in acute cough. Nineteen studies reported adverse effects of these medications and described infrequent, mainly minor side effects such as nausea, vomiting, headache and drowsiness.
Quality of the evidence
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 poorly reported making assessment of risk of bias difficult. While all studies were placebo-controlled randomised controlled trials only a minority reported their methods of allocation and randomisation and there was lack of reporting of blinding of outcome assessors and whether cough outcome measures were validated. In addition, studies supported by pharmaceutical companies or other providers were more likely to have positive results. Studies were very different from each other in terms of treatment types, treatment duration and outcomes measured, making evaluation of overall effectiveness of OTC cough medicines difficult.