Poly-Hist DM is part of the Antihistamine / Alpha-1 Agonist / Non-narcotic Antitussive Combinations class and treats Nasal Congestion, Allergic Rhinitis, Cold Symptoms and other conditions. Antihistamine / alpha-1 agonist / non-narcotic antitussive combinations are used to treat cold symptoms, allergic rhinitis, cough, and nasal congestion. They work by suppressing cough, shrinking blood vessels in the nose for congestion and blocking the action of histamine which causes allergic symptoms. Poly-Hist DM is only available as a brand name drug. Get Poly-Hist DM for as low as $75.86, which is 33% off the average retail price of $112.82 for the most common version, by using a GoodRx coupon.