Tachyphylaxis to topical steroid measured by histamine-induced wheal suppression.

Ten healthy volunteers were studied to find out whether tachyphylaxis occurs on repeated application of topical steroids. The Singh and Singh modification of the Reddy and Singh (1976) technique was used. Fluocinolone acetonide cream (0.1%) under occlusion was applied daily for 14 days on the flexor aspect of the forearms. The wheal was induced by pricking with histamine acid phosphate solution and the volume of the wheal produced was calculated. The test was repeated on the same sites on alternate days for 14 days. The maximum wheal suppression, which gradually diminished, was observed on the 8th day. By the 14th day, there was practically total tolerance to topical steroid, which showed minimal suppression of histamine wheal formation. This confirms the occurrence of the phenomenon of tachyphylaxis by different experimental techniques.