Antihistamines are synthetic central nervous system (CNS) depressants whose initial and primary therapeutic utility remains in counteracting allergy symptoms produced by excessive histamine activity (H1-receptor site), along with regulation of stomach acid (H2-receptor site); however, their potential use has greatly expanded with the relatively recent discovery of H3- and H4-receptor sites (Table 1). Histamine, an organic amine that also serves as a neurotransmitter, was discovered in 1910 by Henry Dale and Patrick Laidlaw. Jeff Forneau was the first to synthesize antihistamines, but it was Swiss-born Italian Nobel Prize–winning pharmacologist Daniel Bovet, while working at the Pasteur Institute in Paris with Anne-Marie Staub, who created the original antihistamine thymoxidiethylamine in 1937. This initial anti-histamine was never marketed as it was too toxic for human use, though ...