Children's Benadryl Allergy Chewables provide temporary relief from allergy symptoms for your child, such as runny nose, sneezing, itching of nose and throat, and itchy, watery eyes. This kids' allergy medicine contains 12.5 mg diphenhydramine HCl per dose to help alleviate symptoms and provides relief that lasts 4 to 6 hours. Available in kid-friendly grape flavor, these chewable tablets provide convenient, fast and easy relief for symptoms due to hay fever. Help alleviate your child's allergy symptoms with the brand moms turn to first when they first treat their children's upper respiratory allergies.