Restrictions have been placed on visitors at Connolly Hospital, Blanchardstown, in order to contain the spread of the winter vomiting virus.
The Health Service Executive (HSE) urged members of the public not to visit patients or attend the hospital's accident and emergency (A&E) department unless "absolutely necessary".
"The public are advised not to visit patients in hospital if they are unwell and especially if they have diarrhoea or vomiting. Full recovery for 48 hours is required prior to visiting in-patients," the HSE's Dublin-North East area said in a statement.
"Hand hygiene is the most effective method in preventing the spread of this virus and visitors are requested to wash their hands or clean with alcohol gel before and after visiting patients
"The infection is a frequent cause of diarrhoea and vomiting in the community and is most common during the winter. It is sometimes called the 'winter vomiting bug'.
"The illness is usually mild in nature and gets better without antibiotics, however it may be quite unpleasant and debilitating in small children or older people who are already sick."