Abstract
Despite the frequency of psychiatric comorbidities, substance use disorder must be understood as an autonomous pathology due to its own determinants, semiology and possibilities of evolution, either spontaneous or under treatment. The ease of access to multiple synthetic products via the Internet combined with the creativity of chemists are contributing to the emergence of novel practices ranging from chemsex to purple drank. Addictive behaviours result from a combination of individual factors (biological and psychological vulnerability) and contextual factors (availability and triviality of the toxicant in the environment). Other mental disorders are factors of vulnerability to addictive pathology as well as the addictive behaviours can reveal an emotional or psychotic pathology. The physician needs to hear the patient powerlessness hidden behind the craving and propose a therapy that may be chemical (including substitution treatment) and psychological. Most of the time, social support is necessary to correct the desocializing effects of substance use disorder or addictive behaviours.