Benadryl Allergy UltraTabs Tablets offer effective relief from upper respiratory allergy and common cold symptoms in a small tablet size. Each tablet contains 25 milligrams of the antihistamine diphenhydramine HCI to temporarily relieve allergy symptoms like sneezing, runny nose, itchy throat and nose, and itchy, watery eyes and the common cold symptoms of runny nose and sneezing. Benadryl Allergy UltraTabs Tablets are intended for adults and children ages six and up.