The February 9, 2002 publication of the British Medical JournalCough (BMJ) featured an article that reports on the relative ineffectiveness of over the counter cough medications and the total lack of evidence that these common remedies work any better than placebos. The published research study reported in the BMJ was designed to figure out whether or not over the counter cough medicines are effective for acute cough in adults. This study reviewed 15 clinical trials involving 2166 participants involved in randomized controlled trials.
The outcome indicated that antihistamines was no better than placebo. There was also conflicting data about the effectiveness of antitussives, expectorants, antihistamine-decongestant combinations, along with other drug combinations compared with placebo. This total lack of conclusive evidence lead the researchers to decide, "Over the counter coughing medications for acute cough can't be recommended because there is no good evidence for their effectiveness. Even when trials had significant results, the effect sizes were small and of doubtful clinical relevance."