People who are vomiting are being warned to stay at home and not visit hospital to prevent the spread of infection.
The advice has been issued by the Doncaster and Bassetlaw Hospitals NHS Foundation Trust, and comes after some wards at Doncaster Royal Infirmary were closed because of the norovirus.
The norovirus - better known as the winter vomiting bug - is one of the most common stomach bugs.
Carol Scholey, Lead Nurse for Infection, Prevention and Control at the trust, said:
“The winter months are here again and with it, unfortunately, comes the inevitable increase in our old friend, norovirus.
“Fortunately, all our wards are currently open and free from cases of norovirus.
“However from the end of October to the beginning of December, we did have 12 areas at Doncaster Royal Infirmary affected by norovirus which meant we had to close some wards to admissions.
“Norovirus is extremely contagious and we are still urging everyone to not come into hospital if they are unwell with vomiting and diarrhoea and to please wait at least 48 hours after symptoms have stopped before coming.
“By taking these precautions will help to protect our vulnerable patients.”
People can get norovirus through contact with an infected person or by eating, or drinking, contaminated food, or water, or by having contact with contaminated surfaces or objects.
Ms Scholey added: “Unpleasant to the last, it can spread quickly in close-knit areas like schools, nursing homes and, especially, hospitals.
“Fortunately, Norovirus usually clears up in one or two days and most people can care for themselves with paracetamol, plenty of fluids and rest.
“Symptoms include the sudden onset of projectile vomiting, watery diarrhoea, and some people may also experience headaches, mild temperature and stomach cramps.
“If you suspect that you are victim to the virus, the best thing to do is to stay at home until you are feeling better. There’s no cure, so unfortunately you have to let it run its miserable course.”
She added that people can also take steps to prevent themselves against getting the illness by using basic hygiene methods.
“The simple remedies such as washing your hands regularly, especially before meals and after visiting the toilet is the best defence against the bug.
“We’ll never completely rid our hospitals of unpleasant illnesses such as norovirus; however we can do our best to limit the effect they have.
“By following this advice you can side-step this tricky little bug, ensuring you stay healthy and happy as the nights draw in and the weather turns chilly.”