Based on a patient: dermographism should be routinely investigated before every provocation test.

was positive but the rest of tested benzodiazepines were negative. Previous reports2 suggest that there is no cross-reactivity among benzodiazepines. Diazepam is the most similar benzodiazepine to tetrazepam, the only difference between them is the presence at position 5 on the diazepine ring of phenyl in diazepam and clohexen in tetrazepam, and this cyclohexene conformation could explain tetrazepam sensitisation.9 Our patient also tolerated oral administration of diazepam and other benzodiazepines. Due to the biopsy result and the positive patch test, an oral challenge with tetrazepam was not performed. We have reported a type IV hypersensitivity reaction confirmed by biopsy as an unusual chronic eczematous reaction caused by tetrazepam with probed tolerance to other benzodiazepines.