Beaumont Hospital is asking people to visit their GP before attending the hospital's Emergency Department because of increased volumes.
The ED has experienced a high number of presentations over the past week, which was further exacerbated by an outbreak of the winter vomiting bug and influenza.
In a statement this evening the hospital says it acknowledges the difficult conditions for both patients and staff.
The ED is one of the busiest in Ireland, providing services to more than 50,000 patients each year.