Most Common Co/Cross-Reactants Identified in p-Phenylenediamine-Allergic Patients and Impact on Available Alternative Hair Dyes

Background: p-Phenylenediamine (PPD) is a common component of hair dyes and is also a common contact sensitizer. Rates of sensitization to PPD, among patients presenting for patch testing, range between 2% and 12%. Given the rates of sensitization, hair dyes containing alternatives to PPD have been developed. Objective: This study aimed to determine the most common co/cross-reactants in PPD-allergic patients and to assess if those co/cross-reactants are found in PPD-free hair dyes and thus limit their use by PPD-allergic patients. Methods: We retrospectively reviewed all patch test results of patients presenting to the University of British Columbia Contact Dermatitis Clinic between January 2008 and June 2013. All patients were patch tested with a screening series of 65 to 80 allergens as well as supplemental allergens as clinically indicated. The American Contact Dermatitis Society Contact Allergen Management Program database was queried for hair dyes without PPD and each of the most common co/cross-reactants. Conclusions: Co/cross-reacting to nickel, cobalt, ammonium persulfate, glyceryl thioglycolate, p-toluenediamine sulfate/base, black rubber mix, thiuram mix, or carba mix did not further restrict the number of dyes. Cross-reacting to 4-aminophenol restricted available dyes to 16. Positivity to any of the fragrances restricted patients to 1 nonpermanent dye.