Background: People living with dementia account for a large proportion of deaths due to COVID-19. Family carers are faced with making significant and emotive decisions during the pandemic, including decisions about end of life. Objectives: We aimed to explore the challenges faced by family carers of people living with dementia during the first wave of the COVID-19 pandemic in England, as reported by charity telephone support line staff, who were able to objectively discuss a range of different experiences of many different carers who call the helpline. In particular, we focussed on key concerns and areas of decision making at the end of life. Methods: We conducted a qualitative study using semi-structured interviews with eight telephone support line staff from two UK based charities who support carers of people living with dementia and those at the end of life. Interviews were conducted in the first wave of the pandemic in England in May–June 2020. Results: An overarching theme of uncertainty and reactivity during a crisis was identified, and within this, five main themes were identified: concerns about care transitions, uncertainty in engaging support and help, pandemic-motivated care planning, maintaining the wellbeing of the person living with dementia, and trust, loss of agency and confusion. Conclusions: Family carers may be reluctant to seek support because of fear of what may happen to their relative, which may include hospitalisation and becoming ill with COVID-19, care home placement, or not being able to be with a relative at the end of life. In some cases, a lack of trust has developed, and instead carers are seeking support from alternative services they trust such as nationally known charities.This study was used to inform the development of a decision aid to support family carers making decisions about care for their relative with dementia during the pandemic, who the lack the capacity to make their own decisions.