Peroral challenge tests with food additives in urticaria and atopic dermatitis.

Double-blind, placebo controlled challenge tests with benzoic acid butylhydroxytoluene, butylhydroxyanisole, beta-carotene, beta-8-apo-carotenal, and sodium metabisulfite were made in 44 cases of chronic urticaria, 91 cases of atopic dermatitis, and 123 cases of contact dermatitis, as a comparison group. Positive reactions were seen in four patients, two of whom had urticaria, one atopic dermatitis, and one contact dermatitis. Two of these reactions were caused by the placebo, one in a patient with urticaria and the other in a contact dermatitis patient. For one patient who reacted to the placebo and one who reacted to benzoic acid, the challenges were repeated with positive results in both instances. In nine patients, equivocal test results were produced with all the active substances and the placebo, but in all nine cases, retesting 4 days later produced negative results. This suggests that common food additives are seldom if ever of significance as precipitating factors in chronic urticaria or atopic dermatitis.