Analysis of the Results from the Patch Test to Para-Phenylenediamine in the TRUE Test in Patients with a Hair Dye Contact Allergy

Background: Para-phenylenediamine (PPD) is the primary patch test screening agent for hair dye contact allergy (HDCA). However, no recent studies have been published that describe the results of reactions to patch tests using PPD and hair dyes in Korea. Objective: To analyze the results of the patch tests to PPD using the thin-layer rapid use epicutaneous (TRUE) Test system in patients with HDCA and to investigate patients' awareness that hair dyes contains allergens, which cause the development of HDCA. Methods: Eighty-four patients with suspected HDCA (32 men and 52 women) underwent patch testing using the TRUE Test system and their own hair dyes. The patients' demographic data, behavior associated with hair dyeing, and clinical manifestations of HDCA were examined retrospectively. Results: Positive patch-test reactions to hair dyes occurred in 5.3.6% of patients who used hair dyes, and they were diagnosed with HDCA. Although there was a significant correlation between HDCA and PPD sensitization (p=0.001), only 40% of the patients with HDCA showed positive reactions to PPD. Of the 45 patients diagnosed with HDCA, only 7 (15.6 %) were aware that their hair dyes contained allergens that caused HDCA. Conclusion: This study's findings show that PPD is an effective HDCA marker. However, we propose that investigations on hair dye components other than PPD should be conducted to develop and validate additional predictive HDCA markers.