My neighbors give their Shih Tzu half a children's Benadryl a couple times per week. He has really bad allergies and gets pus in his eyes if not. They've been doing it for years without any problems.
Other than that, 1/2 children's chewable Tylenol before, vet ordered of course. They always remind me of this after vaccinations because muscle by injection site can be sore and like children, they can run a low fever.
