Occupational immediate-type hypersensitivity to Henna in a hairdresser

A case of a hairdresser who developed an immediate-type hypersensitivity with urticaria, rhinitis, and bronchial asthma on exposure to henna is reported. Prick tests with henna 1% in aqua and in ethanol showed positive reactions. Both patch tests and prick tests performed with the dye in henna, lawsone, or 2-hydroxy-1,4-naphtoquinone, which is supposed to be an allergen, had negative results. These results suggest that not only 2-hydroxy-1,4-naphtoquinone but also other still undetermined ingredients of the henna powder should be considered as possible allergen(s).