Benadryl One A Day Allergy Tablets are give a long-lasting treatment. Just one daily tablet provides effective relief from the symptoms of dust, cat and other pet allergies as well as hay fever, leaving you free to carry on with life as normal. It is available from all good pharmacies and major supermarkets. It contains cetirizine (antihistamine). It can relieve symptoms such as runny nose, sneezing and watery or itchy eyes. It can also relieve urticaria (hives or itchy skin rash).