Will Benadryl Calm A Dog?

Much like anything else, it depends on the dog as well as the dosage.

My vet had suggested that I give one of the foster dogs I had once, one tablet of benadryl to try and calm her thru thunderstorms. It didn't work on her, in fact it made her hyper and this was the not the non-drowsy formula too. We wound up having a prescription for her eventually for phenobarbital, which semi worked.

A couple months later I had another foster dog with thunderstorms (again) and tried the benadryl first with him. It worked fine for him!

Check with you vet first though. It is never recommended to give human medicine to animals as their internal systems do not process medication the same way a human's does. Some breeds don't tolerate benadryl well at all either. Plus you vet will be able to tell you (if he recommends it) what dosage and how often it can be used.