The singer, who is currently recovering in a private clinic, is said to be unable to talk and still on a drip and using an oxygen mask.
A friend told the News of the World: "We nearly lost her and the battle is far from over. She is so weak and this horrible illness has taken complete hold of her.
"It got so bad she was literally only hours from death's door. Thank goodness she was diagnosed in time. Even now she can't talk. She drifts in and out of consciousness and when she comes round all she can do is sob.
"There was no news coming out of the hospital because it was all so touch and go. We couldn't give any assurances to fans because there weren't any to give.
The friend added: "The fact is, we came close to losing someone very special. She can't even speak at the moment and doesn't know what's happening to her. All she can do is sob. It's terrifying. And there's no end in sight.
"Seeing Cheryl like this is so painful. She could easily have died. And she's not better, she's not even close. It's still a very serious situation and she's really going to have to battle."
The report claims that Cole's work schedule for the next few months has been cleared, meaning that she is unlikely to appear at the X Factor Boot Camp.
