Robitussin Cough and Chest Congestion products contain both dextromethorphan and guaifenesin to treat both symptoms. Dextromethorphan suppresses your cough while guaifenesin works as an expectorant to clear your chest congestion and help drain your airways.

Active ingredients Robitussin DM contains two active ingredients: dextromethorphan and guaifenesin. Dextromethorphan is an antitussive drug used to help relieve constant coughing. It helps stop your cough by decreasing activity in your brain that triggers your impulse to cough.