Counties Manukau Health is reporting a spike in people reporting to Middlemore Hospital's emergency department as a result of the easing of Covid-19 restrictions.
Clinical director Dr Vanessa Thornton said it had seen a 30 per cent increase in patient numbers from eight weeks ago.
"As social freedoms have returned we have experienced an increase in trauma presentations that require hospitalisation, and sometimes surgery," Thornton said.
"This is not unexpected but it has put pressure on our hospital system. We encourage people to enjoy the festive season but please play safely. At this time of year the most common cause of presentations are alcohol-related that could be avoided."
A spokesperson for Counties Manukau Health said it had enacted special escalation plans, including cancelling elective surgery, to deal with the surge.
"With more people out and about under the red 'traffic light', we are seeing a significant increase in trauma and medical presentations at our emergency department which in turn has put pressure on hospital capacity," they said.
The spokesperson said they expected the pressures to continue this week.
"We have enacted our escalation plan, which has seen the cancellation of elective surgery, and are working with our metro-DHB colleagues to manage admissions.
"We are also working with our primary care colleagues to explore options to manage the demand for services."
They said the ED needed to focus its attention on patients who have life-threatening emergencies and urged patients to get the right care for their condition.
A healthcare worker from Middlemore Hospital's emergency department, who wanted to remain anonymous, described conditions in the unit as "crazy", with some people spending more than 18 hours in the waiting room on Monday.
They said the ED had 160 patients in the department at 4am in the morning, with 84 patients waiting for beds, with none available.
"The patients have been waiting for hours and there's nothing we can do. We are overwhelmed.
"The biggest problem is the nurses and doctors are under so much pressure and people are leaving the profession because of the stress."
New Zealand Nurses Organisation (NZNO) acting nursing and professional services manager Kate Weston said the easing of the Covid restrictions had seen more people who may have been unwell during the lockdown, coming forward to seek treatment.
"So it doesn't surprise me," Weston said.
But she said the scale of the problem was only made worse by the ongoing shortage of nurses.
"Staffing levels have been an ongoing problem in the Auckland region. And it's a region that has had the majority of Covid-19 community cases, the biggest vaccination and testing centres, the largest number of people isolating at home and the MIQ facilities."
She said the fact they all require nursing staff means something had to give.
"It has put a massive strain on a finite resource."
Weston said the closed borders had also limited the ability of DHBs to bring in nursing staff from overseas.
It follows reports from last week where nurses from Hawkes Bay Hospital wrote a letter to management warning of "ongoing serious safety issues within our ED".
Health commentator and former Association of Salaried Medical Specialists (ASMS) executive director Ian Powell said it's too early to say if the surge has been driven by the easing of Covid restrictions.
But Powell said a nationwide shortage of nurses and doctors is a major factor behind the pressures hospital staff are experiencing.