Altnagelvin Hospital has asked people experiencing cough or cold like symptoms to avoid coming to the hospital.
The warning comes as it’s been revealed that the number of swine flu cases in Northern Ireland has ‘more than doubled’ in the past week.
The Public Health Agency said those eligible for the H1N1 vaccine should see their doctor as soon as possible.
Official data shows the number of cases has more than doubled from 56 to 129
The Western Health and Social Care Trust say people should seek medical help in the most appropriate setting as more people are being affected by winter illnesses.
Geraldine Hillick, Western Trust Director of Acute Services, said: “Western Trust hospitals are working hard to provide clinical care in circumstances of increased levels of flu type illnesses along with other seasonal sickness such as the winter vomiting bug, which is prevalent in the community.
“The public can show their support and cooperation for healthcare staff by ensuring that hospital services are freed up to provide for those patients requiring them.
“People who think they have flu and who are normally healthy should be able to recover at home with the usual flu remedies.
“If symptoms do not improve you are advised to contact your GP or your GP out of hours service rather than attend an Accident and Emergency Department which is for people who are seriously ill and require immediate medical assistance.
“The Trust is asking for the public’s cooperation with its Hospital Visiting Policy which has an important role in protecting against the spread of infections.
“People should avoid visiting any of the Trust’s hospitals if they are feeling unwell, particularly if they have coughs, colds or flu-like symptoms; have diarrhoea and/or vomiting; or have any infectious condition.
“Those who are visiting are asked to thoroughly wash their hands or use alcohol hand rub both before and after visiting.
“Visitors, which are limited to two at the patient’s bedside, are asked to respect visiting times and we would advise them not to bring children under-14 to visit.
“Visitors should visit only one patient whilst at the hospital, refrain from sitting on hospital beds and not move among patients and from ward to ward when visiting.”
Dr Brian Smyth, Consultant in Health Protection, at the Public Health Agency said the agency had seen a “continued significant rise” in the number of seasonal flu cases.”