The "fragmented" nature of health and social care services can cause problems for patients with providers sometimes arguing over who has responsibility for giving care, watchdogs have found.
The division of labour and "poor communication" among providers often leads to complaints from family members about care services, a joint report by the Parliamentary and Health Service Ombudsman and the Local Government Ombudsman has found.
In one case study, a leukaemia sufferer named in the report as "Gail" was left without morphine for her final six days alive as neither the council nor the NHS trust made sure the GP prescription for the painkiller was delivered to her.
The report said: "We were concerned about the responses we received from the trust and council on this issue.
"Both asserted it was someone else's responsibility to ensure the prescription was dispensed and administered.
"This indicated a lack of co-ordinated service.
"As a result it is likely that Gail, who was a vulnerable elderly service user, suffered unnecessary pain for approximately six days before she died."
In another case, a severely disabled nine year-old was left out of education for nine months due to a lack of nurses and transport, leading the watchdogs to urge the local council and NHS trust to pay the boy's family £2,325 each.
The report said: "Some of the problems we see arise because of the fragmented way in which health and social care are provided.
"There are moves throughout the country to address this, with some local authorities being given a budget which includes both health and social care. The aim of this is to encourage more joined-up services and better communication between the different aspects of the overall service for service users.
"But meanwhile, we see many complaints where the division of labour and poor communication cause problems for service users."
It continued: "Shared responsibilities can cause problems when organisations are not clear where their individual responsibilities begin and end.
"Sometimes health and social care providers are not clear about their responsibilities.
"In some cases a person will move house or be placed out of area; several providers will then argue that someone else is responsible for providing the care."
The report comes days after the Government announced a £900 million package to help fund social care in England.
The measures, which include allowing local authorities to hike council tax by 6% over the next two years to fund social care, were however criticised by council chiefs, Labour and charities for not going far enough to alleviate the pressure on the sector.