YES! I was told by my vet that I could give my 8 lb Shih Tzu Benadryl twice a day. There is a little tiny 3 on the small oral syringe that I give her when she has extra problems sneezing. I wash her up at night and give it to her then. She is then clean and isn't sneezing and we can snuggle!!! You might want to check with your vet on the amount for your dogs poundage.
Yes. The dosing is about one milligram per pound, once or twice daily. The adult pills are about 25 mg. Give the medicine in the morning when you're going to be home and awake though. One of my dogs gets a little sleepy with it, and the other gets really super hyper to the point that I had to stay up with him petting him and (yes I actually did this:) singing to him until three am, otherwise he would act like my lap was a trampoline and jump on me, bark several times, jump down, bark more, run 90 miles an hour around the house, come back, stare at me, bark like crazy, jump on me, and so on it went. Good luck!