HELP~~Any ideas on what to take for Hives?

Hey there, Last night I came down with a case of hives.  I have them from head to toe and they are driving me NUTS.  This happend about two years ago and they gave me Zyrtec and BAM they went away immediately, Now the problem is I have no idea if I can take the Zyrtec or not.  I have put a call in to DR. B's office, but have yet to hear from them.  I have my 3 month follow up with him tomorrow, but I need something NOW !  Anyone have any ideas on what I can take for this. Thanks

Thanks Lexi  Dr. B's office finally called back and said either Benedryl or Zyrtec would be ok. Thanks for your help.