One in 10 unpaid carers who called 999 or took their loved one to A&E did so because they did not know where else to go, a report by Carers UK suggests.
Their snapshot online survey also found that one in five used A&E because they could not get hold of a GP or district nurse.
The charity said a lack of local care and support services was contributing to a rise in A&E visits.
There are about 6.5m unpaid carers in the UK looking after a family member.
The Carers UK report, Pressure Points: carers and the NHS, is published as the NHS prepares for a rise in hospital admissions and A&E visits during the winter months.
It is based on data from two surveys – one on how carers use emergency services from 2015 and another, from 2016, on support for carers after their family member is discharged from hospital.
From 5,000 people who responded to the first survey, just over 1,000 said they had called 999 or A&E in the previous 12 months because of health concerns for the person for whom they cared.
While more than 60% of carers said their use of A&E could not have been prevented, about one-third said the emergency admission could have been avoided.
They said better support for the person they care for and more local support for them as carer would have helped.
When asked about their relative’s discharge from hospital, more than half of carers said it came too soon and the right support wasn’t in place at home.
Helena Herklots, chief executive of Carers UK, said the current situation was piling more pressure on an already stretched NHS.
“With more and more families picking up caring responsibilities and older people with care needs being encouraged to stay at home for longer, a step-change is urgently needed to boost investment in community services and involve carers in decisions about the support they, and their loved ones, need to manage at home.”
A Department of Health spokesman said the government was determined to make health and social care more integrated.
“Local authorities are being given more money – up to Â£3.5bn extra – for adult social care by 2019/20 and by 2020 we will be investing an extra Â£10bn a year so the NHS can introduce its own plan for the future and help fewer people go to hospital in the first place.”
He said the government was also committed to giving everyone access to routine GP appointments at evenings and weekends by 2020.
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