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Sensitivity to histamine H1-antagonists has mainly been observed with phenothiazine and ethylenediamine, and is very rare with hydroxyzine. We report 3 cases of sensitization to hydroxyzine, which was prescribed to treat urticaria and atopic dermatitis. A generalized maculopapular eruption appeared shortly after taking the drug. Patch tests with Atarax tablet were positive +3, and +2 or +3 with different dilutions of hydroxyzine. Patch tests with ethylenediamine, piperazine and other antihistamines were negative; therefore, there is no cross-allergy. We believe these rapid systemic reactions to hydroxyzine after the initial dose may have been due to prior systemic sensitivity to this drug, which cannot be used topically. Allergy to antihistamines must be considered when cutaneous lesions worsen on such therapy.

The aim of this study was to evaluate the possibility of cross-reactivity between ketoprofen, fenofibrate and benzophenones because of their structural similarities. Seven patients presenting photodermatitis from ketoprofen underwent patch and photopatch tests. Ketoprofen, fenofibrate, benzophenone 3, benzophenone 10, benzophenone 4, personal medications and topical creams were tested. All patients had positive patch or photopatch tests to ketoprofen and fenofibrate, four patients had positive UVA photopatch tests to benzophenone 3, and two to benzophenone 10. Patients presenting photosensitization to ketoprofen may also have cross-reactivity to fenofibrate and some benzophenones.

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