Self‐harm is a major challenge in healthcare systems. Emergency department nurses provide care to numerous patients with self‐harm injuries. Accordingly, nurse–patient interactions are vital to improve the physical and psychological outcomes of this complex patient group. Previous studies have proposed the establishment of improved teaching programs to increase the competence of emergency department nurses within mental health care; however, few studies have comprehensively investigated the experiences and suggestions for future nursing practices. Therefore, we gathered in‐depth knowledge of Danish emergency department nurses' experiences caring for patients who self‐harm and obtained their suggestions on future nursing practices. Ten semi‐structured interviews were conducted to capture the nurses' individual perspectives. The scientific theory is based on phenomenology and hermeneutics. Interpretative phenomenological analysis was used, and three themes were identified: (i) importance of having the competences to establish a relationship in the acute phase; (ii) acute care from a biomedical perspective; and (iii) highlighting ideas for improved future practices. The emergency department nurses were aware of the importance of mental health care but found their competence and motivation situated in medical care. The nurses felt that they lacked skills to undertake in‐depth mental care for patients who self‐harm and that the healthcare system failed to help this group of patients. Based on these findings, rather than aiming at improving nursing skills, we suggest a close collaboration between the emergency and psychiatric departments to improve the quality of care for patients who self‐harm. We also recommend organizational changes within the emergency department, such as the introduction of a so‐called ‘social track’.