Comparison of Perceived Itch Induced by Skin Prick-tests with Histamine and Codeine

The role of personal factors makes it difficult to correlate subjective data, such as those obtained with the use of a visual analogue scale, and objective data, such as a quantity of injected histamine. In this study, prick tests with histamine and codeine on the forearms allowed a coherent variation in itch scores to be obtained over time, with highly significant differences from controls and with a peak at 4 minutes. These tests are therefore valuable for screening anti-pruritic agents. A significant difference between initial scores and scores for new prick tests after 7 days suggest that tachyphylaxis persists.