The NHS trust responsible for Derriford Hospital has confirmed it is on the highest level of alert, OPEL 4, formerly known as 'Black Alert.'
According to guidance from the NHS, the hospital's status means pressure 'continues to escalate' leaving organisations 'unable to deliver comprehensive care'.
The pressure continuing to mount on the service could have an impact on the basic care patients receive.
They confirmed this escalation was trigged by an influx of emergency patients following the double-decker bus crash in Devon at the weekend.
A spokesperson for University Hospitals Plymouth NHS Trust, which manages Derriford Hospital, said: "We've been very busy since the incident at the weekend and yes we're on OPEL 4."
37 people were injured, eight seriously, after a double-decker bus overturned in Devon.
Emergency services declared a "major incident" after the collision on the A385 Totnes Road, between Totnes and Paignton, at around 11am on Saturday (October 5).
Derriford Hospital is encouraging the public to phone 111 or go to the Minor Injuries Unit, instead of A&E.