Dysparenting, referring to inappropriate parental attitudes, is a vulnerability factor for mental disorders during adolescence and a therapeutic leverage, yet clinicians lack reliable tools to assess it in daily clinical practice. Moreover, the effect of this dysparenting on the amount of psychiatric care remains unclear. The Family and Care study aims to develop the at-risk family interactions and levers (ARFIL) scale, a comprehensive 30-item clinical scale, and to assess in a cross-sectional design, the impact of these at-risk family interactions on the care of adolescents (n = 425) hospitalized in psychiatry and aged 13–19 years old. Factorial analysis shows that the ARFIL scale consists of three main dimensions associated with cohesion/conflicts, love/hostility, and autonomy/control with good psychometric properties. Multivariate regressions show that the ARFIL intensity score predicts the duration of hospital care, regardless of age, gender, medical severity on admission, assessed by the Global Assessment of Functioning scale, the presence of maltreatment and psychiatric diagnoses. Moreover, the ARFIL diversity score (number of items present regardless of their severity) predicts both the number and duration of hospitalizations. At-risk family interactions are a determining dimension of psychiatric adolescent care, and the ARFIL scale could constitute a valuable tool, not only for holistic evaluation and treatment, but also for prevention.