Can I give my dog the same medication I give my other one?

My male yorkie (9lbs.) has allergies and my vet told me to give him half a tablet of benadryl. Now my second dog (female maltese weighing about 6 lbs.) has allergies as well. I don't want to spend so much money at a vet visit to get a yes/no answer! Costs too much! =/ Can I just give my maltese the same medication I give my yorkie which is half a tablet of Benadryl?