About loratadinesecond generation h1 antagonist, antihistamine.mechanism of action of loratadineloratadine blocks one type of receptor for histamine (the h1 receptor) and thus prevents activation (activation releasing other chemicals which produce the symptoms associated with allergy) of cells by histamine. drug also has mast cell stabilizing property.indications for loratadine1. allergic rhinitis (perennial and seasonal ) 2. vasomotor rhinitis 3. allergic conjunctivitis 4. urticaria( mild, uncomplicated ) 5. angioedema 6. amelioration of allergic reactions to blood or plasma 7. dermatographism 8. adjunctive therapy in anaphylactic reactions 9. decongestant