Can you give a dog Benadryl Allergy(not sinus)?

She has been having itching in her ears. We did start taking her to a new groomer. That could be the problem!! :) I hope it is, well she is going in on Monday morning so for now I have Benadryl allergy(not sinus) Active ingredient is Diphenhydramine 25mg. That is it then it has the inactive ingredients. (do you need to know those?) She weights 75 pounds.(Shar Pei mix :) )