Beaumont Hospital is reporting an outbreak of Norovirus - the winter vomiting bug.
Beaumont have said it has been experiencing increased pressure in recent days on the Emergency Department and other services due to the outbreak.
Visitor restrictions have been put in place.
Only one visitor per patient is permitted during visitor hours and children are not allowed to visit in any circumstances.
The hospital is urging people to seek advice from their GP rather than attending the ED.