Contemporary health services are primarily designed around single diseases. People with multimorbidity (multiple long-term health conditions) often become burdened by accumulated treatments. Through multimodal fieldwork in a socially disadvantaged London borough, we explore how people living with multimorbidity navigate conditions of ‘chronic crisis’, encompassing ill-health, overmedicalisation, polypharmacy and social exclusion. Participants in our study frequently experience ‘existential stuckness’, exacerbated by processes of social exclusion. We argue that diagnoses and treatments should account for people’s unique aetiologies, and prioritise the notion of ‘flourishing’ over ‘cure’ as the absence of disease is not always achievable. To foster this emphasis on flourishing, we advocate for a dialogical turn in diagnostic processes that better support patients’ existential needs in the context of long-term illness.