Contact dermatitis to para-phenylenediamine in hair dye following sensitization to black henna tattoos - an ongoing problem

Background: The increased frequency of case reports of allergic contact dermatitis from non-permanent black henna tattoos in recent years shows the popularity of this form of body painting. Patients and methods: Seven patients presented with allergic contact dermatitis after initial hair or eyelash dyeing. They all had a history of a previous reaction from a black henna tattoo. All were patch tested with the European standard patch test series and the standard supplemental series, as well as special series for dyes and hairdressers. Results: All seven patients showed a positive reaction in patch testing with para-phenylenediamine (PPD) (0.3% and/or 1.0% in pet.). Five patients also had positive reactions to other dyes such as aminophenol, para-toluene diamine, disperse orange and yellow and four patients reacted to benzocaine. These were interpreted as cross-reactions. The time from sensitization by the black henna tattoo to the onset of allergic contact dermatitis after hair dyeing was an average of 6.2 years. Conclusions: The most common cause of allergic contact dermatitis after black henna tattoos is PPD. Both the long skin contact and the high concentrations of PPD increase the risk of sensitization. Allergic contact dermatitis may be followed by post-inflammatory hyper- or hypopigmentation, scarring and lifelong sensitization, which can have occupational impact, especially for hair dressers and cosmeticians.