An obsession with NHS targets and spending is "killing patients", according to North Somerset MP Liam Fox.
The ring-fencing that protects NHS spending must end, he has warned David Cameron.
Liam Fox, the former Defence Secretary and Shadow Health Secretary, told The Times the idea that money could solve the health service's problems had been "tested to destruction" and despite massive investment Britain still lagged behind other countries.
Citing the Mid Staffordshire scandal, he said that an obsession with targets and spending was "killing patients" and warned that there were still huge levels of waste within the NHS.
Dr Fox, who was a GP before he was elected as an MP, said that the Prime Minister had been right to increase NHS spending until 2015.
But he added that a pledge to increase spending must not be repeated in the Conservatives' next manifesto, as health was taking up an increasing share of public spending and hampering the ability of ministers to move money to other critical projects.
"I think we've tested to destruction the idea that simply throwing lots more money at the health service will make it better," Dr Fox told The Times.
"The increase over the last decade has been phenomenal and yet a lot of our health indicators lag behind other countries, particularly things like stroke outcome or a lot of cancer outcomes.
"We've become obsessed with throughput and not outcomes and that has been hugely to the detriment of the patients in our system. If you treat the National Health Service itself as being the important entity, and not the patients, then you're on a hiding to nothing."
Dr Fox said that he would accept an invitation from Mr Cameron to return to the Government.
His other points raised in the interview with the Times included him warning Tories not to launch personal attacks on Ukip candidates or the party's supporters.
He also called for aid to be withdrawn from nations that did not share Britain's values, and said that the Tory party would need to pledge "totemic" tax cuts in its election manifesto.