Computerized analysis of concomitant contact allergens.

A statistical study was conducted on 3697 patch-tested patients in order to find any cross-reacting or concomitant allergens. 44 correlations were found. 3 were well-known cross-reacting substances (e.g., benzocaine and p-phenylenediamine). 7 were unlikely, probably random, findings and the remaining 27 were considered to be either new cross-reacting allergens (e.g., promethazine and azo dyes) or concomitant allergens found in the same kind of products (e.g., nickel and cobalt in alloys, ethylenediamine and neomycin in Kenacombin cream, colophony and carba-mix in adhesive bandage).