Z-Tuss AC is part of the Antihistamine / Opioid Combinations class and treats Allergic Rhinitis, Cold Symptoms and Cough. Antihistamine / opioid combinations are used to treat cough and cold symptoms. They work by suppressing the cough and blocking histamine which causes the symptoms of stuffy nose, runny nose, itchy throat, and sneezing. Z-Tuss AC is only available as a brand name drug.