Patients have been asked to consider whether they could use NHS 111 or visit their GP or pharmacist.
However, the hospital added that anyone needing emergency treatment should continue to go there.
Staff at the NHS Suffolk and North East Essex Integrated Care Board, external (ICB), which plans and purchases local healthcare services, have also issued advice about the virus as it can rapidly spread.
Lisa Nobes, the ICB’s nursing director, said: “Every year there are cases in the community which transfer to the hospital.
“Because the virus has an incubation period of several days, people are often unaware that they are carrying it until after they have passed it on.
“Norovirus is spread by coming into contact with infected people or surfaces. If you have the symptoms of norovirus it is important you stay away from work or school and avoid socialising with others.”
Nobes added the best way for people to avoid catching the virus was to wash their hands properly, especially after using the toilet or handling food.