One of the largest pickets in the country has been placed on Cork University Hospital, where around 5,000 people are employed, the majority of them trade union members.
Pickets were placed on the hospital from 8am by four unions: the INMO, SIPTU, Fórsa and the IMO.
In a statement, HSE South West said it is expecting significant and widespread disruption to services, with the cancellation of all elective surgery, routine hospital procedures, out-patient appointments, community-based services, clinics in primary care and other scheduled care services.
It said administrative services will also be impacted. All appointments for today will be re-scheduled.
The emergency department at Cork University Hospital and those at other hospitals in the region remains open and other time-sensitive healthcare services, such as cancer treatment and dialysis, are continuing.
The HSE is urging patients who require urgent medical attention to seek help or to attend their nearest emergency department.
Assistant Director of Industrial Relations at the INMO Liam Conway said some cover had been agreed nationally for contingencies for “life-preserving” cover.
“There will be staff covering the emergency department, the intensive care unit, critical care, in-patient and maternity services,” Mr Conway said.
He added that there had also been a specific derogation for cancer treatment that cannot be re-scheduled, such as chemotherapy and radiation therapy.
Mr Conway said the hospital was already in a state of “black escalation”, due to “significant over-crowding”, and hospital management were trying to maximise discharges ahead of the strike.
Seventy-three patients were waiting for a bed at Cork University Hospital yesterday, 56 in the emergency department and 17 in wards elsewhere in the hospital.
Mr Conway accused the Government of failing to come to the table with a credible pay offer to tackle the cost of living crisis his members are enduring.
“Nurses and midwives in Cork see the consequences of Government’s spending decisions every single day,” he said.
“We see it in understaffed wards, in the growing levels of burnout among our colleagues, and in the constant goodbyes to nurses and midwives who are retiring early or leaving Ireland to seek better opportunities elsewhere.
“At the same time, our members are struggling with the rising cost of living, with the cost of the weekly shop a constant concern.”
The pickets at Cork University Hospital will be lifted from 4pm.
Non-urgent procedures cancelled

Members of the Fórsa trade union outside Nenagh Hospital, Tipperary
HSE Chief Clinical Officer Dr Colm Henry has said that the strike action will result in the cancellation of all non-urgent procedures.
Speaking on RTÉ’s Morning Ireland, he said that there has been a derogation granted by the unions to allow emergency cover at hospitals and GP surgeries are open.
He said that the widespread disruptions to health services include cancellation of all outpatient appointments, as well as hospital community services, planned procedures, community services, data services, clinics in the community, older care, and mental health disability.
Dr Henry said that home care as well any other planned care will not be available.
Day services for people with disabilities are also closed as are Section 8, Section 39 services like St John of Gods, Brothers of Charity, the Irish Wheelchair Association.
Despite the strike, Dr Henry urged anybody who is urgently sick to not delay seeking treatment.