Around 5,000 medical appointments were cancelled following an unprecedented nurses strike which paralysed parts of the NHS.
Healthcare workers in Northern Ireland said they were tearful and “at the end of their tether” after years of under-staffing and sliding pay rates compared to England and Wales.
Stormont politicians stepped up efforts to restore devolved powersharing and urged immediate action to address a “humanitarian” crisis in health.
Routine medical appointments have been cancelled, minor injury units closed and there were delays to some ambulance responses.
Pickets formed across the region and thousands of nurses walked out in their first ever strike.
Joanne Stephenson, a nurse at the Ulster Hospital on the outskirts of Dundonald, said: “People have got to the end of their tether, there’s only so much good will.
“They are working overtime, they are not getting breaks, they are not getting a chance to do what they want to do and they are going home and there’s tears, there’s real tears about what staff want to be able to do but can’t do.”
The action saw thousands of members of the Royal College of Nursing (RCN) leave patients’ bedsides on Wednesday morning for 12 hours, supported by other healthcare workers including paramedics.
At one stage the total of cancelled medical appointments sat at 4,749, not including district nursing visits.
It included daycare and planned inpatient appointments, a fast lane breast clinic, endoscopy procedures and community-based clinics.
Crowds of demonstrating healthcare workers protested outside hospitals across Northern Ireland in an unprecedented show of anger at pay levels they say are lagging behind counterparts in England and Wales and under-staffing.
RCN Northern Ireland director Pat Cullen said: “They have tolerated this for so long and they say today enough is enough and we need to see something change for patients.”
The political vacuum caused by the collapse of powersharing at Stormont means no ministers are in place to decide whether to grant the pay demands or use extra cash to reduce Northern Ireland’s long waiting lists for treatment.
Efforts to resurrect the devolved institutions by next month are ongoing but unionists want the British Government to step in.
Ulster Unionist leader Steve Aiken said: “For humanitarian reasons we need to have direct rule for our health service.”
He added: “For the sake of our health service let’s do something and do it now.
“We can find the money, let’s give the money to the workers, that is what we should be doing.”
A short distance from Stormont, at the Ulster Hospital in East Belfast, more than 100 striking nurses and healthcare workers gathered either side of the main gates for a noisy protest.
A speaker played music and car horns from passing motorists sounded constantly in support. A few ambulances turned on sirens in a show of solidarity.
A newly-qualified registered nurse in Northern Ireland earns £1,875 less than the same role in Scotland and £1,419 less than in England and Wales. For a specialist nurse, the difference is up to £4,677, the RCN said.
Civil servants running public services cannot find enough extra cash to satisfy the RCN, while just under 2,800 posts remain unfilled.
Last year the NHS in Northern Ireland spent £52 million on temporary agency nurses and the RCN believes that money could be reallocated to tackle shortfalls in permanent workforce numbers.
Nearly 300,000 people in Northern Ireland were on a waiting list for a first appointment with a consultant, according to Department of Health figures published last summer.
Sinn Fein and the Democratic Unionists, Northern Ireland’s two largest parties, suffered some reverses in last week’s General Election.
They face another Assembly election if they do not agree by next month to return to powersharing and retake the tiller over increasingly-stretched public services.