Effects of menthol and cold on histamine-induced itch and skin reactions in man

The effects of cooling and topical application of menthol on histamine-induced itch, wheal and flare reactions of the left lower arm were investigated in a threefold cross-over design with 15 healthy male volunteers. Lowering skin temperature by cooling from 32.8 ± 0.3°C to 29.7 ± 0.5°C reduced itch intensity from 260 ± 47 units to 55 ± 12 units (visual analogue scale) and flare diameters from 39.0 ± 2.0 mm to 30.2 ± 1.8 mm; wheal reactions were not affected. A similar reduction in itch was found under menthol (42 ± 14 units) although skin temperature was not decreased. These findings suggest a central inhibitory effect of cold sensitive A-delta fibre activation on itch.