People with serious mental illness have higher morbidity and mortality rates than general populations, and overweight/obesity-related conditions are prevalent. Psychotropic medications are a primary factor in significant weight gain. Adolescents and young adults, particularly those with first-episode psychoses taking atypical antipsychotics, are susceptible to weight gain. This paper reports findings from an integrative review of research investigating the impact and treatment of psychotropic-induced weight gain. Four databases were searched, yielding 522 papers. From these and hand-searched papers, 36 research reports were systematically classified and analysed. The review revealed people experiencing psychotropic-induced weight gain perceive it as distressing. It impacts on quality of life and contributes to treatment non-adherence. Weight management and prevention strategies have primarily targeted adults with existing/chronic illness rather than those with first-episode psychoses and/or drug naiveté. Single and multimodal interventions to prevent or manage weight gain produced comparable, modest results. This review highlights that the effectiveness of weight management interventions is not fully known, and there is a lack of information regarding weight gain prevention for young people taking psychotropics. Future research directions include exploring the needs of young people regarding psychotropic-related weight gain and long-term, follow-up studies of lifestyle interventions to prevent psychotropic-related weight gain.