Allergic reactions in tattoos and permanent make-up are rare but they could be problematic. The clinical presentation and the histopathology are diverse and often confusing. Symptomatic treatment is frequently unsuccessful and invasive techniques can be required. Patch testing to identify the causative allergen is disappointing. The composition of the inks is complex; organic and inorganic colorants, auxiliary components and by-products must be considered. Physical factors such as ultraviolet and laser irradiation could play a role in haptenization of colorants in the skin. Clinical observation and advanced diagnostic methods can be helpful in the diagnosis. Preventive systematic skin testing with tattoo inks, apart from being time-consuming and expensive, is useless.