Lives could be put at risk by reductions in health service funding, a union has warned.
Unite, which represents many health workers, has submitted its response to the draft budget.
Health Minister Michael McGimpsey has warned 4,000 jobs could be lost in the health service because of budget cuts.
To provide an efficient service, officials said they need £5.4 billion by 2015 - instead they are to get £4.6 billion - a shortfall of £800 million.
Unite regional industrial organiser Kevin McAdam said: "Any further reduction in funding would be unsustainable and would put lives at risk."
According to the Department of Health, the elderly and the most vulnerable could be worst hit by stringent cuts. It has been pressing for extra cash. Finance Minister Sammy Wilson has pledged to ring-fence health spending and pointed out that a large proportion of the budget is spent on health.
Mr McAdam added: "The proposals will have the impact of large scale redundancies and the removal of whole services which we believe will have the damaging effect of downgrading health provision in Northern Ireland.
"The issue of safety of patients is paramount in this argument. Staff currently struggle to meet increasing demands on their abilities, to reduce further the number of staff will be to introduce unsafe working, short cuts and risk patient safety."
The British Medical Association of doctors also submitted its response, with Danny Lambe, secretary of the BMA in Northern Ireland, saying: "Overall, BMA is concerned at the lack of detail contained in these proposals and the ongoing political wrangling that has led to a very short timeframe to respond.
"We believe that the DHSSPS should take a more imaginative Northern Ireland-wide approach to organising and managing the health service here."