Effect of acupuncture on experimentally induced itch.

We evaluated the effect of acupuncture on histamine-induced itch and flare in healthy volunteers (n = 25) and compared it with the effect of a pseudo-acupuncture procedure and of no-intervention in a single-blind randomized cross-over study. A cumulative itch index is defined and was found to be smaller with acupuncture than with either pseudo-acupuncture (p less than 0.02) or with no-intervention (p less than 0.005). The duration of itching was shorter with acupuncture than with either pseudo-acupuncture (p = 0.006) or with no-intervention (p less than 0.001). In addition, maximal flare area was decreased with acupuncture compared with pseudo-acupuncture (p less than 0.04) and with no intervention (p = 0.003). Acupuncture had little or no effect on the itch onset time or on the maximal itch intensity after intradermal injection of histamine. Measurements of itching correlated poorly with measurements of flare size in all three experimental groups. Acupuncture appears to be an effective inhibitor of histamine-induced itch and flare. Moreover, acupuncture points displayed specificity in that needling near-by, non-acupuncture sites resulted in greater itching and larger flares.