Beaumont Hospital is restricting visiting hours at the hospital in response to an increase in cases of the winter vomiting bug.
The hospital has seen 30% of patients at the hospital showing symptoms of the Norovirus, or winter vomiting bug.
The public is being asked not to visit the A&E unit or the wards in an effort to protect patients from the spread of infections.
Visiting may only take place between 2pm and 4pm and between 6pm and 8pm, with only one visitor allowed per patient.
Children are not permitted to visit in any circumstances.