Frail and vulnerable patients are being trapped in an "endless cycle" of going in and out of hospitals in England, the British Red Cross is warning.
The charity said the pressure on the NHS meant hospitals were rushing some patients home before they were ready and without adequate checks being made.
It said its staff had found patients in distressing situations, sent back to homes with no heating or lighting.
Hospitals are meant to coordinate care for frail patients on discharge.
But the Red Cross said that simply was not happening because of the lack of community services available from councils and the NHS.
It meant there were growing numbers of patients being readmitted soon after leaving hospital because they were getting no help, the charity said.
It pointed to a report last year that suggested the number of readmissions within 30 days of being discharged had risen by nearly a quarter in the past four years.
The study - based on Freedom of Information responses from hospitals - suggested close to one in 20 admissions was likely to be a repeat admission.
The charity said it wanted to see automatic home checks for every frail patient on discharge.
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Its report highlighted a number of cases, including:
- a woman who had been in hospital for two months sent home with no help and a fridge full of mouldy food
- frail patients with conditions such as broken hips being returned to homes where the gas or electricity had been cut off during their hospital stay
- a man on crutches taken home by ambulance at 23:00 and left in the car park outside his home
The charity said the lack of support patients received increased the risk of falls in particular.
'Falling between gaps'
Red Cross chief executive Mike Adamson said his teams had first-hand experience of the problems being encountered as they provided support to about 300,000 people across the UK after being discharged from hospital.
He said: "The NHS is rightly a source of national pride, but despite the best efforts of hardworking doctors and nurses we know many of our hospitals remain under serious pressure this winter.
"When the system is strained, all too often it is frail, older people who live alone that are falling into crisis in the gap between hospital and home."
His comments come on the day the NHS in England released figures showing the pressure hospitals are under.
They showed bed-occupancy rates were once again at unsafe levels across the NHS.
Dr Nick Scriven, of the Society of Acute Medicine, which represents doctors looking after patients brought in as an emergency, said staff were becoming "increasingly anxious" about the pressures they were working under.
A Department of Health and Social Care spokeswoman said what the Red Cross had documented should not be happening.
"We expect local authorities to work closely with the NHS to ensure people are treated in the most appropriate setting and when they are discharged from hospital they have a care plan in place."
The Local Government Association called it a "telling" report and said a lack of funding was impacting on the ability of councils to provide care.