I've heard that certain Antihistamines, such as Benadryl, are relatively effective as a Polygraph countermeasure, mainly because antihistamines (especially stronger antihistamines) reduce your body's response to just about everything. Is this statement true?
What are some other quick & easy ways to "beat" the polygraph test? Are there other drugs out there that are proven to be reliable countermeasures against the polygraph?
No, antihistimines are not relatively effective as a polygraph countermeasure. The key to passing the "control question test" (the most commonly used polygraph technique) is to produce stronger reactions to the so-called "control" questions than to the relevant questions.
You'll find a detailed explanation of the "control question test" and effective countermeasures in Chapters 3 & 4, respectively, of The Lie Behind the Lie Detector (http://antipolygraph.org/pubs.shtml).