Zyrtec is an oral antihistamine designed to provide fast allergy relief for symptoms such as sneezing, runny nose, sore throat, and itchy watery eyes. Union Chimique Belge (UCB), which was founded in Belgium by Emmanuel Janssen in 1928, developed Zyrtec in the 1980s. The company ... Read More originally focused on producing industrial chemicals before it expanded into the pharmaceutical field; now it sells products that aid in allergy relief, respiratory disease, and central nervous conditions such as epilepsy and Parkinson's disease. Zyrtec fights against indoor and outdoor triggers such as dust, mold, pet dander, pollen, and grass to relieve allergies for up to 24 hours at a time. The antihistamine comes in a number of forms including tablets, liquid gels, and D tablets that start working within one hour and also help relieve congestion. Zyrtec 10mg 24 Hour Allergy Tablets are designed for adults and for children 6 years and older to relieve indoor and outdoor allergies for a 24-hour period; they start working after just one hour. Its compact size makes it easy to keep a box handy in a purse or backpack.