Allergy Cetirizine Antihistamine | Hayfever | 30 Allergy 10Mg | 24 Hour Allergy for Dust, Pets, Runny Nose & Hives | Adults and Children over 6 Years. Cetirizine Antihistamine : Allergy / Hayfever starts working within hour to relieve sneezing, runny nose and allergy-related itching caused by pollen, dust, and pet dander.