Juan Manuel Correa has been placed in an induced coma after being diagnosed with respiratory failure upon his arrival at a new hospital in London.
The American-Venezuelan suffered broken legs and a spinal injury in the crash which killed Anthoine Hubert in the Formula 2 feature race at the Belgian Grand Prix.
After undergoing treatment in Belgium, Correa was transferred to London for specialist care, where his latest symptoms were discovered.
A statement from the Sauber junior's parents read: "Honouring our son’s straight-to-the-point and honesty that characterises him, we wish to update you on the status of his injuries and physical condition.
"As time has progressed, new complications have surfaced as a consequence of the massive impact he suffered Saturday in Belgium. On his arrival to London, Juan Manuel was diagnosed with Acute Respiratory Distress Syndrome.
"This is an injury considered common in high impact accidents such as this one.
"Unfortunately, this injury resulted in Juan Manuel falling into Acute Respiratory Failure. Juan Manuel is currently in an Intensive Care Unit that specialises in respiratory injuries. At this point of time he is an in induced state of unconsciousness and under ECMO support. Juan Manuel is in critical but stable condition.
"We are confident that our son will surprise us like he always does with his tremendous fighting will and strength and will recover completely."