The hospital has urged patients whose condition is not life-threatening to consider seeing their GP or visiting Corby Urgent Care Centre because their own A&E department is under excessive pressure.
A hospital spokesman said: "Please be aware that if you attend A&E and your condition is not life-threatening or urgent, you will be facing a longer wait before treatment because we are treating our sickest patients first.
"If your need is less urgent please consider your own GP who may now be operating extended hours, or attending Corby Urgent Care Centre, where you will be seen by a doctor, your wait will be a lot shorter and parking is free."
A bid to create a £46m Urgent Care Hub at the hospital to tackle overcrowding was given Government approval in October last year.
The hospital's A&E department currently sees more than twice the number of patients it was originally built for.
Patient levels have reached 100,000 people in a year with the hospital's chief executive Simon Weldon admitting it created privacy and dignity issues and a poor working environment for staff.