Radio Doctor Illawarra general manager Frank Wallner says the after-hours service is being swamped by call-outs for the flu.
Mr Wallner said the service has been struggling to keep up with demand in the past few weeks - often needing to respond to multiple patients in the one place.
It comes as flu cases continue to rise in the region - with the number of confirmed cases now surpassing 1500 since January.
That compares to the 616 cases recorded throughout the Illawarra Shoalhaven Local Health District for the entire 12 months of 2018.
"There's been a definite upswing in call outs for flu in the last few weeks - and often there's multiple patients in the one household or nursing home," Mr Wallner said.
"We are a little restricted with being able to recruit doctors willing and able to work at night, and on weekends, and it's hard when we're unable to meet the demand.
"In those cases we have to refer people to telephone services or in more serious cases to the emergency department - putting further strain on those already stretched resources."
Mr Wallner said Radio Doctor Illawarra was working with other health services to meet the demand of this year's flu season.
"We need a funded, co-ordinated and integrated strategy for after hours medical care in the region," he said.
"And that needs to include input from all stakeholders including the health district, ambulance, and the primary health network."