Background: There are an estimated 46.8 million people worldwide living with dementia in 2015, being cared for usually by family members or friends (informal caregivers). The challenges faced by informal caregivers often lead to increased levels of stress, burden and risk of care-recipient institutionalisation. Aim: The overarching aim of this study was to explore the experiences and perceptions of informal caregivers of people with dementia when interacting with the health care system, and whether the support received acted as a mediator of caregiver stress. The secondary aim was to investigate healthcare professionals' views and current practice regarding people with dementia and their interactions with informal caregivers. Method: We employed a qualitative research design, using focus groups and one face-to-face interview with a purposive sample of informal caregivers and healthcare professionals in Lincolnshire, UK. Data were collected between March and July 2015. We used the stress-process model of stress in caregivers as a theoretical framework. Results: We interviewed 18 caregivers and 17 healthcare professionals. Five themes, mapped to the stress-process in caregivers' model, captured the main challenges faced by caregivers and the type of support they wanted from health care services. Primary stressors included the challenge of diagnosing dementia; caregivers' needs and expectations of an in-depth knowledge and understanding of dementia from healthcare professionals; and need for carer education. Secondary role strain included lack of support and mismatch of communication and expectations. Caregiver involvement in monitoring care and disease was a potential mediator tool. Conclusions: Fragmentation of dementia care services, lack of training for healthcare professionals and the dearth of information for caregivers means health care services are only partially fulfilling a support role. In turn, lack of support may be intensifying caregiver stress leading to worsening in their health and well-being; thus, potentially increasing the risk of institutionalisation of their care-recipient.