General surgery ward nurse Helen Adair said she was speaking to the media because management was not listening.
The "hugely unsafe" situation put some patients at risk, she believed.
Her ward - 4C - had had an increase in high-needs patients recently which exacerbated the situation.
The 31-year-old, from Bournemouth, England, felt "guilty" for going public, but had "hit a wall".
Ms Adair says her concerns are shared by other nurses.
Nurses were frequently in tears, and morale was extremely low, she said.
Sick-leave rates were high, which she suspected could be due to overwork.
Nurses sometimes had inadequate rest time between shifts, which they were often asked to pick up at short notice.
Gaps were not filled when nurses were away, or nurses were pulled in from other wards to help for short periods.
After the Otago Daily Times approached the DHB for its response yesterday morning, senior management approached Ms Adair, resulting in a promise of a meeting with staff.
After putting her concerns directly to senior managers yesterday afternoon, Ms Adair said she had a better understanding of the situation, including the lack of agency nurses in Dunedin.
She was concerned, however, that the DHB cited new patient management software, known as TrendCare, as the solution. Its benefits would not be fully realised until mid-2013 and an interim solution was needed immediately, she said.
Not having enough staff meant delays to procedures like administering intravenous antibiotics and dressing patient wounds. The longer wounds were open, the greater the risk of infection.
Nurses were also challenged prioritising tasks such as cleaning patients who had soiled themselves, she said.
Requests to hire healthcare assistants to undertake low-level tasks had gone unheeded.
Management tended to cite budget constraints to nurses.
Ms Adair had initially feared sanction for speaking out to the media, but said she had become frustrated. "If I get fired, I get fired".
Southern DHB chief midwifery and nursing officer Leanne Samuel said when contacted Ms Adair faced no sanction for speaking out.
Ms Samuel said 4C was not understaffed, but she acknowledged the "entire fourth floor" was busier than usual and was being monitored.
The DHB was making the best use of resources it could, she said.
The TrendCare software helped managers keep a close eye on all parts of the hospital.
A major IT patient management project, the system would not be fully rolled out until the middle of next year.
Another Dunedin Hospital nurse, who did not wish to be identified, said the hospital was the most unhappy place at which she had worked.
In the past two months, she had seen many nurses leaving wards crying from stress and frustration.
The DHB seemed to lack a casual pool of nurses who could be called in at short notice, which was unusual for a major hospital, the nurse said.
Senior management did not communicate with staff, leaving middle managers to take the flak, she said.
Earlier this month, at the DHB's hospitals advisory committee meeting, a report showed the nursing budget to March was nearly $1.6 million under budget. Asked about this, Ms Samuel said the situation had changed and she expected the nursing budget to be overspent by the end of the financial year.
