The measure referred to in the introduction to define the concept of medicines in accordance with European regulation is as essential to emphasize the dual role :
- Purpose of the drug, independent of an actual effect (by virtue of their designation, presentation drugs)
- Existence of pharmacological, immunological or metabolic effect in the treated human or animal organism (by virtue of their function, functional medicine).

This means that there are both items that are for the purpose of treating or prophylaxis used, or intended to be used (even when should they act in fact not healing or disease prevention) classified as medicines, like products that bring the no claim to salvation, but because of their special composition of an enhancer. This classification is important because drugs are covered by another law as food, cosmetics or medical devices (the problem of product differentiation).