Antihistamine / alpha-1 agonist / non-narcotic antitussive combinations are used to treat symptoms of the common cold, allergies, and the flu. These medications work by combining an antihistamine to reduce allergy symptoms, an alpha-1 agonist to relieve nasal congestion, and a non-narcotic antitussive to suppress cough. They are available in oral forms, such as syrups and tablets. Examples include dextromethorphan / doxylamine / phenylephrine (NyQuil Cough DM Plus Congestion) and brompheniramine / dextromethorphan / pseudoephedrine (Bromfed DM). You can choose the form that best fits your needs.