Yes, Vicodin is a hydrocodone/APAP mixture. APAP is basically acetominephen or Tylenol. Vicodin is pretty much the same as Lortab, if you're more familiar with that.
I can give you the possible SE:confusion, nausea, vomiting,dry mouth, constipation,urinary retention,and in sensitive individuals...possible itching, rashes, wheals and anaphylaxis and hypotension.
Mild itchiness isn't that uncommon....how bad is yours? Maybe check in with your dentist if it's worrysome.
Hope this helps.