A financial crisis in the health service is "inevitable", a leading health charity has warned.
There is a "looming" financial disaster in the NHS which will arrive by 2015/16, the King's Fund predicted.
This would have "damaging consequences" for patient care such as rising waiting times, cuts in staff and "deteriorating" quality of care, it said.
The health charity said that a "significant" boost in funding for the NHS is needed to prevent the impending crash.
Yesterday the Office for National Statistics (ONS) highlighted that s pending for health services "slowed significantly" between 2009 and 2012.
The ONS said growth of healthcare between 1997 and 2009 was "strong" with an average annual growth rate of 8%. But since 2009 growth slowed to an average of 1.6% each year.
The latest report from the King's Fund says that a quarter of NHS trusts are already in deficit and a financial crisis is "now inevitable by 2015/16 and could arrive sooner".
"On its current trajectory, the health and social care system in England is rapidly heading towards a major crisis," the report states.
Lead author of the report John Appleby, chief economist at the King's Fund, said it is now a question of when, not if, the NHS runs out of money.
The pressure facing the health service has been "exacerbated" by the introduction of the Better Care Fund, which will draw £1.8 billion of funds from the NHS to support joined-up working between health and social care services from April next year, the report adds.
Additional NHS funding should not just be used to "prop up unsustainable services", the authors cautioned.
It should instead be invested in developing new models of care outside hospitals - where treating patients is the most costly .
And it should also be given to "otherwise sound" NHS organisations experiencing difficulties because of strain on their budgets.
The main methods for cutting down on costs, such as freezing salaries, have almost been exhausted, the authors said. But there are still a number of ways to improve efficiency.
"There is still scope to improve efficiency in the health service, and efforts to release savings should be re-doubled," said Mr Appleby.
"However, it is now a question of when, not if, the NHS runs out of money.
"Without significant additional funding, this will lead to rising waiting times, cuts in staff and deteriorating quality of care.
"It is essential that politicians from all parties are honest about the scale of the financial pressures facing the NHS and initiate a public debate about the long-term sustainability of the health and social care system before, not after, the general election."
A Department of Health spokeswoman said: "The difficult economic decisions this Government have taken has meant we have been able to protect the NHS budget and as a result the NHS is performing well despite rapidly-rising demand.
"To ensure the NHS is sustainable in the long term, we need to continue to invest more in out-of-hospital care, make better use of technology and innovation while never compromising on the quality of care."