A Penn State College of Medicine study has shown that many over-the-counter cough medicines are no better than non-medicated syrup for nighttime cough and sleep quality in children with upper respiratory tract infections.
The study, titled "Effect of Dextromethorphan, Diphenhydramine, and Placebo on Nocturnal Cough and Sleep Quality for Coughing Children and Their Parents," was published in the July 2004 issue of Pediatrics.
"Consumers spend billions of dollars each year on over-the-counter medications for cough," said Ian Paul, M.D., assistant professor of pediatrics, Penn State Children's Hospital, Penn State Milton S. Hershey Medical Center. "Our study showed that the two ingredients used in most over-the-counter medications were no better than a placebo, non-medicated syrup, in providing nighttime relief for children with cough and sleep difficulty as a result of upper respiratory infection."
From June 2002 to May 2003, study volunteers ages two to 18 were recruited from patients with upper respiratory infections at two practices affiliated with Penn State Hershey Medical Center. Once consent was obtained from parents, parents were asked to answer questions about their children's conditions, such as cough severity, cough frequency, and the effect of the cough on sleep, using a seven-point symptom severity scale. Symptoms, as reported from the parents, had to reach a certain threshold for children to be admitted to the study. Then, each child was randomly assigned to receive dextromethorphan (often abbreviated as "DM"), diphenhydramine (an over-the-counter antihistamine) or placebo. Neither the physician nor parent knew which of the three the child would take.
Parents were instructed to give the medication to the child 30 minutes before bedtime. The next day, a second survey was administered to parents asking the same questions as the day before. (The study was approved by the Institutional Review Board under federal regulations at Penn State Milton S. Hershey Medical Center.)
Of the 100 children with upper respiratory infections included in the study, 33 patients received dextromethorphan, 33 received diphenhydramine and 34 received placebo. Patients were ill an average of 4.21 days before participation in the study. The symptom scores from the night before treatment were compared to those after treatment.
"All three groups, including the non-medicated syrup group, showed dramatic improvement, with scores for cough frequency, impact on child and parent sleep, bothersome nature of cough, and severity of cough scoring lower," Paul said. "Neither dextromethorphan nor diphenhydramine was superior to placebo for any outcomes studied in this trial."
Not only was there no significant improvement for the children who took cough medicines with the active ingredients, but in the cough frequency category, those who received placebo reported a 2.24-point improvement in cough frequency, whereas the parents of those who took the medicines with active ingredients reported only a 1.97-point improvement.