The main objective of this paper is to achieve a comprehensive understanding of addiction. Primarily, through the principles of the theory of self-medication, which to the greatest extent explains the psychological aspect of the background or basis of addiction, with the addition of relevant knowledge from other theories and models that complete the behavioral, sociological and neurological basis. Such an overview of information, settings and models seems necessary, for the sake of the complex and multidimensional nature of addiction, and therefore for understanding and, ultimately, treatment. The most important results obtained from the work refer to the key role of the inability to regulate affect and relationship regulation, which according to Edward Khantzian, the author of the theory of self-medication, are key aspects for understanding and then treating addiction. The basis of the treatment is an empathic and non-judgmental approach to the person, who through this relationship has the opportunity to re-experience certain experiences, affects and traumas that often occurred in early developmental periods or during life and their resolution. In this way, it is ensured that the reasons that lead an addicted person to addiction or to relapse are resolved. In addition to the psychological part, interventions are necessary in the areas of motivation for change, learning to control affects and impulsivity, increasing the ability to self-control, changing harmful beliefs, adequate social support, and changing compulsive behavior. Considering that social workers often coordinate and connect a large number of activities and processes that addicts go through during treatment, it is important primarily to understand the basis of addiction, which in this work is self-treatment, and then the key areas of work in order to provide the person with adequate support and reduced the inevitable difficulty of this process, as well as suffering and the likelihood of relapse.