Continuous usage of a hair dye product containing 2‐methoxymethyl‐ para ‐phenylenediamine by hair‐dye‐allergic individuals

Summary Background Despite a positive patch test reaction to para ‐phenylenediamine ( PPD ) and/or toluene‐2,5‐diamine ( PTD ), many people attempt to continue dyeing their hair with products containing PPD or its derivatives. Objectives Investigation of elicitation reactions among PPD / PTD ‐allergic individuals to hair dye products containing the less sensitizing PPD derivative 2‐methoxymethyl ( ME )‐ PPD . Methods Elicitation reactions were studied in 43 PPD / PTD ‐allergic individuals by a 45‐min pretest with an ME ‐ PPD ‐containing hair dye on their forearm. Upon a negative result this was followed by exposure to subsequent hair colour treatment(s). Results Overall, 38 of 43 PPD / PTD ‐allergic individuals did not develop an elicitation reaction during the pretest with ME ‐ PPD ‐containing hair dye products, and were eligible for subsequent hair colour treatments. Of these 38 PPD / PTD ‐allergic individuals, 29 tolerated subsequent hair dyeing with ME ‐ PPD ‐containing hair dye products, while seven showed mild and two showed moderate/marked allergic reactions upon the first hair colour treatment. Conclusions Hair dye products with the less sensitizing ME ‐ PPD were tolerated by 29 of 43 (67%) PPD / PTD ‐allergic individuals throughout continued hair dyeing with an average of nine treatments per year. Five individuals reacted upon pretesting, while only mild‐to‐moderate/marked skin reactions occurred upon hair dyeing in nine individuals who were not identified by the pretest. To our knowledge this is the first study among PPD / PTD ‐allergic individuals indicating that a negative 45‐min pretest with a hair dye product helps to avoid severe allergic reactions.