About Desloratadine Second Generation long-acting tricyclic H1 Antagonist, Antihistamine. Mechanism of Action of Desloratadine This second generation antihistamine has a selective peripheral H1-antagonist action.Desloratadine competes with free histamine for binding at H1-receptors in the GI tract, uterus, large blood vessels, and bronchial smooth muscle. This inhibit the action of histamine, which subsequently leads to temporary relief of the negative symptoms brought by histamine Indications for Desloratadine 1. Hay fever 2. Watery eyes 3. Runny nose 4. Itching eyes 5. Sneezing 6. Hives 7. Decongestant Typical Dosage for Desloratadine Adult (general dose)- 5mg/day Children (>12yrs)-Same as adult