Topically applied aspirin rapidly decreases histamine-induced itch

The effect of topical aspirin and its model vehicle dichloromethane on itch experimentally induced with histamine was studied in 16 subjects, using a visual analogue scale and computerized aspirin, but not its vehicle, significantly reduced itch duration (p = 0.001) and decreased itch magnitude as measured with a visual analogue scale (p < 0.04). Histamine injection caused elevation of warmth sensation threshold (p = 10(-8)) but did not affect cold and heat pain thresholds. Aspirin and vehicle application did not affect thermal and pain thresholds during histamine-induced itch. The current data suggest that topical application of aspirin may be beneficial for the treatment of histamine-mediated itch. Its therapeutic role in the management of clinical itch remains to be determined.