Zyrtec® Allergy Relief 10 mg Strength Tablet 60 per Bottle (1170230_BT) 1/BTAlleviates common seasonal allergy symptoms, including sneezing, runny nose and itchy, watery eyes, nose and throat Zyrtec tablets contain 10 milligrams of the active ingredient cetirizine HCl and come in the original prescription strength. They work quickly and last for up to 24 hours. This formula works on both indoor and outdoor allergens.