Delayed hypersensitivity reaction from black henna tattoo manifesting as severe facial swelling.

We report on a 14-year-old boy who was presented to the emergency department with an acute swelling of the face and scalp 3 days after using a new hair dye. The patient had applied a black henna tattoo 1 year earlier. Patch testing revealed an allergy to the potent skin sensitizer paraphenylenediamine, a common ingredient of hair dyes and also found in black henna tattoo. It is important for emergency physicians to be aware of the possibility of a delayed type-IV hypersensitivity reaction from black henna tattoos manifesting as an acute contact dermatitis. These patients may have gross facial swelling but should not be treated for angioedema.