Time-dependent inhibition of histamine-induced cutaneous responses by oral and intramuscular diphenhydramine and oral fexofenadine

Diphenhydramine tended to work more rapidly than fexofenadine, but the differences were not statistically significant. Given the adverse effect profile of diphenhydramine, but only marginal onset of action advantage, the risk-to-benefit ratio may be more favorable for oral fexofenadine when treating an acute urticarial or allergic reaction.