Allergic contact dermatitis caused by skin painting (pseudotattooing) with black henna, a mixture of henna and p-phenylenediamine and its derivatives.

BACKGROUND: Skin painting (pseudotattooing) with henna is traditionally performed mainly in Muslim or Hindu persons. Recently, transient artists have begun using black henna mixtures to temporarily paint the skin. Emergence of allergic contact dermatitis after application indicates the presence of a skin sensitizer in such preparations and poses future risks. OBSERVATIONS: Four patients developed allergic contact dermatitis after skin painting with black henna performed in France, Egypt, and the United States. The delay of symptoms suggested previous sensitization in 1 patient and active sensitization in 3 patients. Of 3 patients who underwent patch testing, the results were positive for p-phenylenediamine in 3 patients and for p-toluylenediamine in 1 patient. These sensitizers are found in hair dye preparations.
CONCLUSIONS: The mixtures used by the artists possibly contained natural henna, a rare and weak skin sensitizer, and likely contained chemical coloring agents, diaminobenzenes, such as p-phenylenediamine and/or diaminotoluenes. The long duration of skin contact, the high concentrations of sensitizing materials, and the lack of a neutralizing agent dramatically increase the risk of skin sensitization, which is why such substances are prohibited for direct skin application. Because of the worldwide vogue of skin painting, future cases of sensitization to p-phenylenediamine and diaminobenzenes or diaminotoluenes are expected.