Six wards at a Norfolk hospital are restricting patient visiting to one hour a day because of a continuing outbreak of norovirus.
Queen Elizabeth Hospital at King's Lynn has been hit by the condition, which causes sickness and diarrhoea.
Bays have been closed on wards treating patients for diabetes, respiratory and urology conditions.
Medical assessment wards and specialist units for the elderly patients are also affected by the continuing outbreak.
Visiting to the six affected wards is being limited to one hour in the evening, from 1900 BST.
A hospital spokesman urged anyone who had been suffering from nausea, vomiting or diarrhoea in the past three days not to visit.
Anyone who has come into contact with someone showing these symptoms in the past week should also stay away, he said.