The HSE has issued an appeal to people seeking medical care or assessment to consider all options before going to a hospital Emergency Department.
It expects it to be one of the busiest ever periods experienced by the health service.
The Health Service Executive says while some patients will experience long wait times in Emergency Departments, urgent patients will always be prioritised.
The appeal comes as all out-patient appointments for University Hospital Limerick have been cancelled today, only urgent elective surgeries will go ahead at the hospital "over the coming days".
A "major internal incident" was declared at the hospital due to unprecedented levels of attendance yesterday.
In a statement, the Hospital group said the "unprecedented" number of people attending the Emergency Department has been driven by a surge in respiratory infections, including Covid-19, flu and RSV.
The HSE has appealed to people to consider all options before going to hospital this week including visit your local pharmacy if feeling unwell.
GPs are also running additional clinics during the time of high pressure. Its advising if you need to urgently see a GP outside their clinic hours, you can contact your local GP out-of-hours service.
Pressure is being put on the health system as Covid-19 and influenza cases continue to increase rapidly.