Patients are being asked to stay away from Stoke Mandeville Hospital as it is experiencing unusually high admissions.
Anyone experiencing vomiting and diarrhoea should not go to hospital unless told to by a doctor and should stay away for 48 hours after symptoms subside.
People are advised to consider all other options, such as a pharmacist, NHS Direct and out of hours GP services.
The hospital trust said in a statement: “It is important that you call 999 if you are seriously unwell or critically injured.
“We remain fully committed to treating patients who need our services and thank you for your assistance.”