Temporary holiday "tattoos" may cause lifelong allergic contact dermatitis when henna is mixed with PPD.

Temporary tattoos are becoming more popular especially among teenagers. For this purpose henna tattoos are usually used. Although pure henna is relatively safe, combining it with other colouring agents such as para-phenylenediamine (PPD), may cause skin sensitisation. Several cases of contact allergy from temporary tattoos have been reported, each with positive reactions to PPD. Six cases of allergic contact reaction to temporary tattoos are reported. In all cases, the responsible agent was PPD. Two were also allergic to black 'henna' hair dye which also contained PPD. They had been sensitised on earlier holidays by their temporary tattoos. Temporary holiday tattoos may cause lifelong contact allergy. Although the allergenicity of pure henna is low, the allergenicity of PPD is high. Holiday 'tattoo' reactions are going to be common until PPD is removed from the mixture.