Samantha Reynolds has complained to Blackpool Victoria Hospital about the treatment of her father Sydney Marks, 77, who was discharged last Wednesday after spending 10 days in hospital after being diagnosed with a brain tumour.
Mr Marks has been given just weeks to live and also has the early stages of dementia.
His daughter says she had arranged for him to be transferred to Fairhaven Lodge care home, where her mother resides, so the pair could spend precious time together.
But instead he was taken back to his home in Beech Avenue, Warton, by taxi.
He was left outside for several minutes but, because his daughter lives on the same road, she spotted him by the side of the road in his dressing gown, with no house keys.
Hospital bosses have said they will investigate.
She said: “It shouldn’t have happened and I’m absolutely furious about it.
“Luckily I was in otherwise I don’t know what he would have done.”
Mr Marks was admitted to A&E after suffering a seizure in the shower, later being transferred to Royal Preston Hospital on September 8 for an outpatient appointment where he was diagnosed as having between three and four weeks to live.
He was then sent back to the Vic where his daughter was offered use of the patient transport service, which provides non-emergency ambulance transport to and from hospital, to take him to the care home where she had arranged for him to be admitted so he could be with her 73-year-old mother Ann.
However, he was returned by taxi instead to Beech Avenue at around 5pm last Wednesday, where Samantha found him by the side of the road.
She added: “I’m just so upset and angry about the whole manner of his care and I don’t want it to happen to somebody else. I knew he couldn’t go to live back home because he wasn’t steady on his feet and couldn’t dress by himself.”
Samantha has complained to Gary Doherty, chief executive of Blackpool Teaching Hospitals NHS Foundation Trust, which runs the hospital, about the matter.
She has received a reply acknowledging her complaint.
Mr Marks will now go into Royal Preston Hospital later this week to discover whether an operation to prolong his life slightly by removing part of the tumour can take place.
A spokeswoman for the Trust said: “Blackpool Teaching Hospitals Foundation Trust is sorry to hear of a patient’s concern about discharge.
“We are unable to discuss individual patients, but can confirm we have received a complaint which will be investigated fully. When we have concluded our inquiries we will be in touch with the family directly.”
Deborah Parker, operations manager for Lancashire at the Alzheimer’s Society, said: “It is concerning to hear of these circumstances and the distress that it has caused the family.
“People with dementia are vulnerable members of society and can become disorientated when out of their normal routine, which can add to their anxiety.
“Alzheimer’s Society is here to help support people with dementia to live well and their loved ones and are working with organisations, businesses, Blackpool Council and healthcare providers to make the borough more dementia-friendly.”