Hydroxyzine Pamoate is an antihistamine used to treat hives, itching, rashes, and various skin conditions that occur during an allergic reaction. It is also prescribed as a mild sedative or tranquilizer for dogs having anxiety problems. Side effects can include, dizziness, drowsiness, blurred vision, dry mouth or vomiting. In the case of any side effect, it is important to notify your veterinarian.