People are being urged to stay away from Tasmania's two major public hospitals unless it is an emergency because of significant demand for services.

The state's health department issued the advice on Tuesday night for the Royal Hobart Hospital and Launceston General Hospital.

Both facilities and Ambulance Tasmania are experiencing high rates of unplanned staff absences with COVID-19, the flu and other seasonal illnesses circulating in the community, the department said.

There are also a high number of patients with complex needs awaiting discharge, including people waiting for placement in aged care and National Disability Insurance Scheme assessments, approvals and support.

"The hospitals are closely managing elective surgery activity to maintain access for emergency demand," department of health secretary Kathrine Morgan-Wicks said.

"This includes working with private hospitals to access contracted bed capacity and elective surgery support."

Australian Nursing and Midwifery Federation state secretary Emily Shepherd said the current emergency department situation in the two hospitals was incredibly difficult.

"(It is) the worst it has ever been," she told ABC Radio.

"That's not just my personal opinion - that is the voice of our members right across the state and from seasoned nurses who have worked in this health system for decades."

The health department says people can contact urgent care clinics in Hobart and Launceston if their issues are not an emergency.

In July, just 36 per cent of all emergency department patients at the Royal Hobart Hospital were seen within the recommended time, with the figure 37 per cent for Launceston General Hospital.

Both figures were worse than the previous month.