What Is the Difference Between Calamine and Caladryl?

Caladryl lotion contains calamine and diphenhydramine, which is the active ingredient in the antihistamine Benadryl, according to WebMD. Caladryl and calamine are both over-the-counter preparations used to treat the itching associated with poison oak, ivy and sumac; bug bites; and minor skin conditions such as acne.