Benadryl will not hurt them. Follow the weight directions as you would for a child. They make a child's formula that melts on contact in the mouth which should bring fast relief, but you will need to give it every 4 to 6 hours. It's more important to find out WHAT caused the allergic reaction and remove it permanently. If the reaction isn't better by the second dose, then you should contact a vet. Again, find out what caused the reaction.
