[Allergy to topical antihistamines--discrepancy between the literature and clinical practice]

In a prospective study, 100 patients suffering from allergic contact dermatitis were tested for allergy to antihistamines. Diphenhydramine was chosen as test substance because it is the most widely used topical antihistamine in Europe and is, moreover, prescribed for several indications. Not one of the 100 patients proved to react positively on patch testing. The bad reputation among allergists of topically administered antihistamines, which is based on reports in the American literature claiming a high risk of epicutaneous sensitization, thus appears unjustified on the basis of our own data and the lack of European reports of this problem. The adverse findings in the USA may be due to their frequent use of a particularly potent contact sensitizer as emulsifier in topical preparations in general and antihistamines in particular.