The WHO (World Health Organization) defines drug addiction as "a state of physical or psychological dependence or both, between a product and a person followed by a periodic or continuous use of it".

Drug addiction represents alienation and deprivation of freedom because the drug addict is deeply dependent to his drug.

For some people, drug addiction is an adaptation strategy that allows a person to anesthetize, by taking drugs, his impulses, his incompetence feelings, that is to say a depressive state that feeds despair and bad living anchored at the bottom of themselves, even from their childhood.

For others, drug addictions takes part of a hedonist, egocentric antisocial life-style, adopted even before their initiation in the world of drugs, the pursuit of pleasure is their life goal, at a minimal price effort.

It is manifested in three different ways:

Dependence :  Drug addiction is base in the incapability of stop taking products or substances.

Tolerance : Drug addict’s body gets adapted to drug effects and it is necessary to increase the doses to obtain constant intense effects.

Acclimatization : The result of a repeated use is the desire of it.