Expectorant / non-narcotic antitussive combinations are used to treat cough, chest congestion, and mucus buildup caused by the common cold and bronchitis. These medications work by thinning mucus in your airways, making it easier to cough up, and by suppressing the cough reflex. They come in different forms, including oral tablets and syrups. One popular example is guaifenesin / dextromethorphan (Mucinex DM, Robitussin DM). You can choose the form that best fits your needs.