Two wards at Dunedin Hospital are under tight restrictions because of a diarrhoea and vomiting outbreak.
Ward 6a was closed to patient admissions and visitors, while ward 8b was closed to visitors, and admissions were restricted.
Anyone considering visiting the hospital was asked not to if they had recently experienced gastroenteritis symptoms.
The outbreak had put pressure on other parts of the hospital, and some elective surgery has been postponed, Southern District Health Board said in a statement.
The board is encouraging the public to see their GP early, and use the after-hours service, in a bid to reduce patients presenting at the emergency department.
Patient services director Dick Bunton said staff had responded "incredibly well'' to the situation.
"Dunedin Hospital is experiencing a high number of acutely unwell patients presenting in ED this week, leading to increased admissions.
"Family and friends are also being asked not to visit patients in Dunedin Hospital if they have diarrhoea and vomiting symptoms, and for 48 hours after the symptoms are cleared because they can still be infectious.''
Earlier this week, an outbreak had closed ward 6b to new patients and visitors. It reopened on Tuesday.
