Influence of grenz rays and psychological factors on experimental pruritus induced by histamine and compound 48/80

The interaction between grenz rays and experimentally induced pruritus was evaluated in 14 healthy subjects. Grenz rays were administered once weekly for 4 weeks on restricted areas of the upper arms. Pruritus was evoked by intradermal injection of histamine and the histamine liberator compound 48/80. The results were compared with unconditioned values and with those obtained following a placebo treatment procedure. The influence of psychosocial and psychosomatic factors was also evaluated. Grenz-ray therapy reduced itch but not flare responses. The influence of grenz rays was, however, not statistically different from that observed after placebo treatment. Psychosocial and psychosomatic factors were good predictors of individual skin responsiveness. The results indicate that grenz rays do not interfere with experimental histamine-induced pruritus more than placebo and emphasize the importance of knowing individual characteristics and coping strategies.