In the United Kingdom, 1.5m partners, friends and family members provide substantial care and support to people experiencing mental health problems. Previous studies have focused on the experiences of such carers in community settings. This study focused on carers of those detained in inpatient settings under the Mental Health Act 1983 who maintain relationships via Section 17 (s.17) leave. Semi-structured telephone interviews with five carers were analysed thematically and identified that carers: struggled with the emotional impact of s.17 leave, experiencing anxiety, guilt, and stigma; experienced practical challenges and self-sacrificed in order to support s.17 leave; but reported positive impacts on the maintenance and development of their and the detained person’s social identities and networks. However, these carers received very little support. Implications for social workers include the need to support carers before, during and after s.17 leave, through supporting their involvement in planning the leave, ensuring that escorted leave is staffed by those known to the carer, raising awareness of carer needs and referring carers for support and/or psychoeducation and a care needs assessment. Social workers are well-placed to take a holistic view and support carers in navigating the challenges that caring for somebody around s.17 leave can bring.