People in Bath who suspect they may be affected by the winter vomiting bug are asked to stay away from the Royal United Hospital.
Norovirus is highly contagious, and can be passed easily from people to people.
At the moment no wards at the RUH are affected by the bug, and staff are asking people who think they have the bug not to visit.
Instead they are asked to call their GP who will decide what action needs to be taken.
A spokesperson from the RUH said: "While norovirus can be a nasty experience it is normally short-lived and people usually recover quickly.
"Patients and visitors are reminded not to come into the hospital if they have had symptoms of diarrhoea and/or vomiting in the previous 48 hours, or indeed have been in close contact with anyone with these symptoms.
"People who are otherwise fit and healthy will make a full recovery from norovirus without any medical intervention.
"If the symptoms persist, or seem to be getting worse ring your GP surgery.
"The triage nurse or GP on call can tell you over the phone if you need to be seen and appropriate arrangements can be made."
