Hydroxyzine‐induced fixed drug eruption and cross‐reaction with oxatomide

There are a few reports in the literature implicating them in causing fixed drug eruption, the piperazine derivatives. In this case, although eszopiclone for insomnia medicinehas a piperazine ring, no eruption appeared so far. Oxatomide and hydroxyzine not only shared a piperazine ring but also shared two benzene rings via a methine group (=CH–). It was suspected that this shared structural group became an antigenic determinant and resulted in cross‐reactivity. Such a unique case has not been reported before.