Three wards at Noble's hospital - 9, 20 and the Grainagh Court mental health facility - have been closed after a norovirus outbreak.
It's described as a small number of patients and staff who have reported symptoms, with the virus confirmed in some of those cases.
The three affected wards have been closed to all new admissions.
A statement from the Department of Health says alternative arrangements have been put into place by the Mental Health service and Noble’s, and patient care will not be affected.
Planned admissions and outpatient appointments will continue as normal.
There's also a reminder to anyone who catches it.
You must wait for 48 hours after cessation of all your symptoms before returning to work or school, as you continue to shed the virus for 48 hours after you have completely recovered.