Mental health crises in adolescents are often variable, reactive, and dependent on interpersonal context. Self-harm, emotional instability, and relational difficulties are clinically important because their severity may change rapidly and may increase clinical risk. The aim of this paper is to discuss assessment of change over time as an element of risk evaluation and treatment planning in adolescents experiencing psychological crisis. This is a narrative clinical review. The paper addresses self-harm, emotion dysregulation, protective factors, developmental differences, family context, multi-informant assessment, and the patient’s individual communication style. Repeated clinical assessment does not replace psychiatric diagnosis or comprehensive safety assessment, but it may improve clinical vigilance, facilitate earlier detection of deterioration, and support more individualized therapeutic decisions.