[Drug use and treatment misuse: Key points on polydrug use].

Problematic use of psychoactive drugs, be it legal, on prescription, or not, remains a broad phenomenon when taken as a whole, with an increasingly large spectrum of used products. The polysubstance drug use is an expanding new trend. Although its epidemiological analysis is complex, needing further research, certain patterns of drug combinations can be found, allowing to identify clusters of users associated to more specific medical and social risks. Managing polysubstance users involves assessing each drug use, but also the connections between drugs and the patient's expectations for each of them. Complications, as well as psychiatric and somatic comorbidities are to be taken into account. The therapeutic tools for polysubstance drug use, mainly pharmacological, are still often limited to the sum of specific tools for each product. Prevention is crucial but has to adapt to the identified use clusters, and the gender. Notably, a good knowledge of chronic pain management and prescribed drug dependency risks is required to prevent polysubstance drug use involving opioids.