The TV host was taken to hospital eight days ago.
Television and radio host Richard Bacon has been placed in a medically induced coma after becoming critically ill.
The former Blue Peter host was taken to hospital with suspected pneumonia eight days ago, after falling ill on a flight to Britain from the United States.
The TV star confirmed his illness on social media last week, praising the NHS for the treatment he had received.
But Mr Bacon’s sister has now confirmed that his condition has worsened, and he has had a tracheotomy to aid his breathing.
Posting on Instagram, Juliet Bacon wrote: “This is my seventh day visiting my brother who’s been in an induced coma since last Thursday, just so grateful to the NHS x”
A source told The Sun: “Doctors started treating him for pneumonia but it soon became apparent that it wasn’t working and his condition took a dramatic turn for the worse.
“They had no choice but to put him into a medically induced coma to save his life because things spiralled so fast, but that was a week ago and they are no closer to finding out what is wrong with him or how to help him
“It’s touch and go, and extremely upsetting for everyone who loves him. They are beside themselves with worry.”
Close friend Dean Jackson, who gave Bacon his first on-air job, also confirmed that medics are attempting to pump more oxygen into his system.
“He is being kept in the coma to get more oxygen into his system but they are hoping to reduce the sedative soon so hopefully there will be good news”, the BBC Radio Nottingham host confirmed.