[Opiates, harm reduction and polysubstance abuse].

Opioid dependence is a chronic metabolic brain disease and several individual, sociological and biological factors are implicated in its development. Program (needle exchange, low threshold access to treatment) prevent harms associated with opioid use (HIV, overdose…). Effective treatment involves a set of pharmacological and psychosocial interventions. The benefits of maintenance programmes increase as long as the person remains in treatment (many years). Relapse is a symptom of the disorder or a sign of abstinence failure. Treatment aims to improve quality of life in a comprehensive and individualised assessment.