The term drug, or psychoactive substance, refers to any substance that can change mental functions and individual behaviour, and thus cause functional or pathological changes in the central nervous system. The use of psychoactive substances to the extend that it is assumed to cause mental dysfunction and behavioral disorder is called drug abuse. The term “psychoactive” does not necessarily mean addiction, but they are used as synonyms: drug usage, drug use and substance abuse. New psychoactive substances are a global phenomenon and a problem that mimics the effect of controlled drugs. Every da there is an increasing number of new substances that arise due to small changes in the chemical structure and therefore we do not find them on the list of drugs, psychotropic substances and plants from which drugs can be obtained. The main procurement route is the internet. Acute intoxication, overdose and death are the biggest problems when it comes to the use of new psychoactive substances because their action requires a very small amount, and users resort to higher doses to achieve greater and stronger effects of the drug. A synonym for new psychoactive substances is “designer drugs”. Designer drugs include: synthetic cannabinoids, synthetic cathinones, and synthetic phenylethylamines. According to the definition of the World Health Organization, drug addiction is defined as a condition of occasional or permanent poisoning caused by repeated use of natural or synthetic drugs. In drug addiction, we have two entities: physical and mental dependence.