P-phenylenediamine hair dye allergy and its clinical characteristics

Background: P-phenylenediamine (PPD) has been identified as the most frequent contact sensitizer of hair dye and the clinical characteristics of hair dye contact allergy (HDCA) are diverse. Objective: The purpose of this study was to identify the clinical characteristics of HDCA and to assess the relationships between HDCA, exposure time to PPD and PPD positivity. Methods: We analyzed 105 patients with patch test-confirmed hair dye allergy who presented between July 2009 and March 2015. Clinical symptoms, signs, associated skin diseases, involved ACD area, and patterns of hair dye use were obtained by reviewing medical records and by interview. Results: HDCA was more common in women and in individuals aged more than 50 years. Pruritus was the most common symptom; erythematous macules and patches were the most frequently observed clinical signs. The most common site of HDCA was the face and non-specific eczema and urticaria were frequently observed with HDCA. Exposure time to hair dye, represented as frequency and duration, showed a positive correlation with the area affected by hair dye allergy (p＜0.001). Hair dye allergy was identified in most patients (80%) before diagnosis by patch test. However, only 28.6% of all patients stopped using hair dye, even after the diagnosis was confirmed. Conclusion: The extent of hair dye allergy involvement was related to exposure time to hair dye. For effective treatment of HDCA, it is important to properly educate patients with HDCA about the clinical manifestations of HDCA and to keep away from allergens.