Public release date: 22-Jan-2008

Over-the-counter medicine is commonly and casually used by millions of cold sufferers every year, but there is no good evidence for or against the effectiveness of OTC cough medicines, concludes a new systematic review of studies.

“I do not give my kids over-the-counter cough medicine,” said Thomas Fahey, professor of general practice at the Royal College of Surgeons in Ireland Medical School and review co-author. “I do not advise my patients to do so.”

Another issue concerned the researchers, who wrote, “six out of the nine studies that were supported by the pharmaceutical industry showed positive results compared to three positive studies out of 16 trials that did not report any conflict of interest.”

On the other hand, “Most preparations appear to be safe based on those studies reporting side effects, which only described a low incidence of mainly minor adverse effects,” the researchers found.

The review of the studies appears in the latest issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews like this one draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.

The Cochrane review encompassed 25 studies, 17 of which involved 2,876 adults and eight of which involved 616 children.

In the adult studies, six compared antitussives medicines used to relieve coughs, such as Robitussin, with placebo and had variable results. Two studies compared an expectorant such as Mucinex, which promotes the discharge of mucus from the respiratory tract, with placebo; one found benefits. Another two studies focusing on combinations of antihistamine and decongestants, produced conflicting results, while three studies found antihistamines were no more effective than placebo in relieving cough.