Greater inhibition of dermographia with a combination of H1 and H2 antagonists.

The dermographic response was measured in eleven subjects with dermographia and chronic urticaria at baseline and after treatment with an H1 antihistamine, an H2 antihistamine and the combination. Greatest inhibition of the dermographic response occurred with a combination of the H1 and H2 blockers (P less than .01). These results support the rationale of using the combination of H1 and H2 antagonists in urticarial disease not responding to H1 blockers alone.