Oral tests in contact allergy to para-amino compounds

A group of 34 inpatients with contact allergy to para-amino compounds (sulfanilamide, paraphenylenediamine, benzocaine) underwent a series of peroral tests using structurally related substances, sulphonvl ureas (carbutamide, tolbutamide and chlorpropamide), diaminodi-phenyl-sulfone. saccharin and salicyl azosulfapyridine. Sulphonyl ureas given orally can produce a widespread dermatitis in subjects with contact sensitivity to sulfanilamide. but not in those sensitized to paraphenylenediamine and benzocaine.