Contact urticaria from cobalt chloride.

Cobalt chloride should be added to the ever growing list of contact urticants. This chemical is frequently used as a color indicator in provocative sweat testing. In this case, contact urticaria was probably nonimmunologic in origin. Since diphenhydramine and 48-80 (polymonine block this reaction to cobalt chloride, vasoactive amines are at least partially responsible for the urticaria.