The trust is overwhelmed by rising patient numbers, winter infections such as flu and norovirus, and staff sickness, leading to significant and unacceptable delays in A&E and on hospital wards.
This marks the fifth NHS trust in the last 24 hours to declare a critical incident, with others in Surrey and Kent also facing similar challenges.
Patients are experiencing lengthy waits, with the Queen's Medical Centre's A&E regularly seeing over 500 patients daily, despite being designed for 350.
The trust is appealing to the public to only attend A&E for genuine emergencies and to utilise other services like NHS 111 for less urgent health concerns.