Benylin Dry Coughs contains Dextromethorphan which helps to suppress the cough mechanism, and Levomenthol, a decongestant which works to help relieve stuffiness in the nose to help make breathing easier. It also contains Diphenhydramine which works to help relieve a runny nose. A dry cough is also known as a non-productive cough because it does not produce any phlegm. Dry coughs are caused by an inflammation of the upper airways caused by dust, foreign bodies or an infection.
