All non-elective surgery has been cancelled at hospitals in the Belfast Health Trust area for the rest of this week and restrictions are also in place at hospitals throughout Northern Ireland due to pressure in accident and emergency departments.
In the past 15 days, 139 people had to wait more than 12 hours to be seen at an A&E department.
All the health trusts said the pressures on staff increased after an extraordinarily busy weekend.
The Belfast Health Trust said its decision to cancel all non-urgent elective surgery for the rest of the week had not been taken lightly and stressed that cancer surgery and emergency cases are unaffected.
It also advised that minor healthcare issues can be dealt with "at home, by a pharmacist or by a GP".
The provision of care services for the elderly also continues to be a major issue in Northern Ireland.
Immediately before Christmas, for budgetary reasons, the Belfast Trust proposed suspending shopping, laundry and cleaning services by home helps for 550 elderly people.
However, the plan was shelved after a public campaign against it.
GP services are free in Northern Ireland, but there is a growing trend of problems with out-of-hours GP availability and members of the public opting to turn up in A&E departments.
Meanwhile, in Britain Labour has called on the government to convene an emergency summit of health, social care, council and emergency services to find ways to ease the pressures on struggling accident and emergency departments.
Several hospital trusts have been forced to activate major incident plans to cope with a surge in demand.
British Prime Minister David Cameron has admitted the NHS is under "pressure" after waiting times in England plummeted to their worst levels in more than a decade.
Mr Cameron dismissed union claims the service was "on the brink of disaster", but shadow health secretary Andy Burnham said a coordinated plan was urgently needed to address a "rapidly deteriorating position".
