Brighton and Hove hospital chief Duncan Selbie urged people to think about whether they really need to go to Accident and Emergency.
He was speaking after 1,000 people turned up at A&E at the Royal Sussex County Hospital in Brighton over the weekend.
He told fellow board members this morning that there were 99 more patients on the wards at the Royal Sussex today than expected.
Steve Holmberg, joint medical director at Brighton and Sussex University Hospitals NHS Trust, pitched in at the Royal Sussex rather than attend the trust board meeting in Haywards Heath.
Mr Selbie said that a lot of work had been done to tackle bed blocking and to ensure patients didn’t stay in hospital any longer than necessary.
He said: “We need more help about not getting people into hospital and more help getting people out of hospital.
“Our front door is just unbelievably busy.
“Over the weekend we’ve had 1,000 people in and this is not sustainable.
“We’re not saying this is somebody else’s problem but there’s not an easy answer.
“People are choosing to come into the hospital rather than go elsewhere.”
At the same meeting the board heard that efforts were under way to save £10 million to ensure the trust did not overspend its budget for this financial year.
Mr Selbie said: “We’re hoping to get through the winter without opening additional capacity.”
Demand for beds traditionally rises during the winter months.
He added that despite the financial pressures, staff would ensure that patient safety was not put at risk.
One member of staff said that the centre of Brighton had been busy on Saturday evening with the White Night celebrations and many hundreds of people out and about in Halloween costumes, adding: “One or two people in A&E looked a lot worse than they actually were!”
