Patch tests with commercial hair dye products in patients with allergic contact dermatitis to para-phenylenediamine.

BACKGROUND: Hair dye is one of the most common causes of allergic contact dermatitis. The main allergen has been identified as para-phenylenediamine. To prevent the recurrence of contact dermatitis to para-phenylenediamine, patients should discontinue the use of para-phenylenediamine-containing hair dye products. However, many patients are unable to discontinue their use for cosmetic or social reasons. Sometimes, they continue to have symptoms even after switching to so-called "less allergenic" hair dyes. OBJECTIVES: To evaluate the safety of 15 commercially available hair dye products in patients with allergic contact dermatitis due to para-phenylenediamine. METHODS: We performed patch tests using 15 hair dyes that were advertised as "hypoallergenic," "no para-phenylenediamine" and "non-allergenic" products in the market. RESULTS: Twenty three patients completed the study and 20 (87.0%) patients had a positive patch test reaction to at least one product. While four (26.7%) hair dye products contained para-phenylenediamine, 10 (66.7%) out of 15 contained m- aminophenol and 7 (46.7%) contained toluene-2,5-diamine sulfate. Only one product did not elicit a positive reaction in any patient. LIMITATIONS: Small sample size and possibility of false-positive reactions. CONCLUSIONS: Dermatologists should educate patients with allergic contact dermatitis to para-phenylenediamine about the importance of performing sensitivity testing prior to the actual use of any hair dye product, irrespective of how it is advertised or labelled.