Two ingredients commonly used in cough syrup are no better than sugar water in suppressing night-time coughing in children, according to a study published on Tuesday. The two ingredients are dextromethorphan -- often listed on labels as “DM” -- and diphenhydramine, an antihistamine. The former is the most common nonprescription cough suppressant on the U.S. market, and commonly abused by adolescents who try to get high on cough medicine.
