||Until the 1990s, children and adolescents were excluded from clinical trials. A pivotal change occurred in 1997 with the FDA Modernization Act which granted six months additional exclusive marketing rights to pharmaceutical companies which conducted FDA-approved paediatric studies. The expanded scope of clinical trials involving children was favoured. After 1999, the annual growth rates for the prescription of psychotropic drugs to children and adolescents dramatically increased. Risperidone, an atypical antipsychotic, is considered now as the best treatment for disruptive behavioural symptoms in children with autistic and other pervasive developmental disorders. The number of scientific publications praising the beneficial effects of Risperidone is impressive compared to those insisting on the Risperidone-associated diabetes mellitus risks and other metabolic problems. How do pharmaceutical companies succeed in promoting their drugs despite huge side effects? How do they succeed in preventing or discarding studies on these side effects? Why do new molecules always seem better than the previous ones? We explored some mechanisms whereby company marketing can both transform the perceptions of physicians and shape the experience of those seeking treatments.