The UL Hospitals Group is urging the public to present to University Hospital Limerick's (UHL) emergency department "only in the event of serious illness or injury".
It is the second such warning issued in the past month.
In a statement issued yesterday evening, the group said UHL is dealing with "an unprecedented level of presentations".
It said 283 patients attended the UHL emergency department in the 24 hours to 8am yesterday morning, making this the single busiest day the department has experienced. One day earlier, 241 people presented to the ED.
"The ED is the Mid-West region’s main emergency treatment admission pathway for Covid-19 patients,” said the group's statement.
"By opting for alternative care pathways, including family doctors, out-of-hours GP services, local pharmacies and minor Injury Units at St John’s, Ennis and Nenagh Hospitals, people will be helping to protect the safety of the most seriously ill patients and our emergency care staff."
It said by considering the alternative options, people will be able to avoid long waits in the ED, relieving pressure on the hospital’s management of the "significant demand for inpatient beds from patients with Covid-19 infection, and those who have been de-listed but continue to recover from the disease".
According to the Irish Nurses and Midwives Organisation, 70 patients were reported as waiting for beds at the hospital — the highest total in any Irish hospital.
The hospital group said not all patients are waiting on trolleys and that most are in designated bed spaces.