[Contact allergy to a new preservative].

A 43 year old woman with no previous skin disease developed contact eczema on the face and neck after application of a lotion used for "smoothing wrinkels", available as a non-prescription item. Patch testing of the product and of one of its ingredients, Euxyl K 400, revealed strong positive reactions. Upon testing of the individual components of the preservative Euxyl K 400, the substance 1,2-dibromo-2,4-dicyanobutane showed a positive reaction even in the concentration of 0.004%. Due to the increasing use of Euxyl K 400 inclusion of the preservative in the patch test battery should be considered.