This article explores a hidden and under-acknowledged dimension of caring in family life: when older people with care needs act in a harmful, abusive or violent way towards the family member(s) who cares for them. Thirty-eight health and social care professionals, working in the UK, took part in five focus groups to explore their experience of working with families in this situation. The group discussions were stimulated by vignettes developed from interviews with carers affected by harmful behaviour, and the data generated using this method were analysed using a thematic approach. There were two principal findings: (i) ‘carer harm’ is a serious and under-acknowledged problem, which practitioners have extensive experiential knowledge of and (ii) practitioners face considerable practical and ethical challenges working with affected families. Drawing on Miranda Fricker’s concept of epistemic injustice, we discuss how contemporary social, legal and policy systems can make it difficult for practitioners to identify and meet the needs of affected families. Finally, we explore the role of social workers—and the support they need as a professional group—to work alongside a ‘hidden’ group of families seeking to manage the intersection of care, harm and intimacy in later life.