The effects of an antihistamine on the mean areas of dysesthesia, wheal, and flare evoked by spicules containing BAM8–22 or histamine. A–E, The mean areas of alloknesis (A), hyperknesis (B), hyperalgesia (C), wheal (D), and flare (E) evoked by BAM8–22 (BAM) or histamine (Hist) applied to skin pretreated with a topical cream containing placebo (Plac) or an antihistamine (Anti). The number of subjects reporting each effect is in parentheses. The antihistamine prevented or significantly attenuated only the sensory effects of histamine. BAM8–22 produced no wheal or flare. BAM8–18 evoked no dysesthesias, wheal, or flare.