Excitability (especially in children) is one of the listed possible side-effects of Benadryl. You can talk to your vet about this. Depending on the intensity or duration of the excitability your vet may recommend a different dosage or prefer to use an injectable steroid prior to vaccination. It is not technically an "allergic" reaction, just an unpleasant one, but any unusually excessive or extreme effect should be discussed with your vet. Debi Christy Ferrets First Foster Home www.ferrets1st.com [Posted in FML issue 5129]