The effect of H1 and H2 receptor antagonists on the dermographic response

The effect on dermographic wealing of an H1 and H2 receptor antagonist was studied separately and in combination. a double-blind protocol was used and dermographism was measured as the diameter of weal response to a measured force. Both H1 and H2 antagonists had a small but non-significant effect, but the combination of H1 plus H2 antagonist had an approximately additive effect which was significant. Although this indicates a role for H2 receptors in dermographism it does not establish the degree of involvement, nor whether H2 antagonists necessarily have any advantage over a potent H1 blocker alone in the treatment of dermographism.