The scientific developments derived from biological research applied to dermatology have profoundly changed numerous concepts in skin physiology and physiopathology. The activity at the level of the epidermis or dermis represents the borderline for dermatological or cosmetic products. In this regard there are three different European Union (EU) directives regulating cosmetics, drugs and medical devices, and the three definitions all refer to the biological structures of the skin. An attempt was made to review the EU regulatory status of these different categories of products. In particular, the definitions were compared trying to identify the borderlines and especially the overlapping parts. Moreover, the possibility to better consider and classify the new functional cosmetics--so-called cosmeceuticals--was also considered.