About cetirizinesecond generation h1 antagonist, metabolite of hydroxyzine, antihistamine.mechanism of action of cetirizinethis drug is a selective peripheral h1 receptor antagonist. thus it inhibits the allergic symptoms produced by histamines like cold, rhinorrhea, sneezing, urticaria etc. the drug has some mast cell stabilizing properties. it also inhibit eotaxin-induced eosinophil tem through both dermal and lung micro vascular endothelial cells. so inhibit eosinophil chemotaxis and also inflammation caused by it.indications for cetirizine1. sneezing 2. rhinorrhoea 3. postnasal discharge. 4. common coughs 5. colds. 6. chronic urticaria 7. dermatitis 8. pruritic skin disorders 9. hay fever 10. angioedema