Patrick,

With regard to your first question, I couldn't say why your polygrapher would have said you were lying about your date of birth or your citizenship. If you were administered a Relevant/Irrelevant polygraph interrogation, then, if these questions were used as irrelevant questions, your polygrapher might have actually been attempting to help you pass by sensitizing you to these questions, rather than the relevant questions. What were the questions that you "exaggerated" about? For further reading on polygraph procedure, see Chapter 3 of The Lie Behind the Lie Detector.

With regard to Claritin, I am not aware that any research has ever been published about its possible effects on a polygraph interrogation. The website DrugDigest.org lists the following side effects for Claritin:
 

Side Effect	Incidence for Claritin (%)
stomach pain	2.0
drowsiness	2.0
dry mouth	1.0
fatigue	1.0
headache	1.0
stomach pain	2.0
general ill feeling	2.0
nervousness	2.0
wheezing	2.0

I have taken maybe four polygraph tests in my apps to different PDs.  I know for sure that I passed two because I was forwarded in the process or hired outright.  The thing I don't get is that in one of the other two, the machine not only said I was lying about things I "exaggerated" about, but things I really can't like my citizenship (US) and my date of birth.  What's that all about?   

Also, I take the allergy medication Claritin and in one of the tests (and only this one) the tester asked me about it.  I informed him that no one else had ever asked me about my medication and he said it changes the "galvanic skin response" and can alter some responses to some questions.  Anybody know anything about that, too??

Thanks for your help.