The X Factor judge was taken out of his house on a stretcher in a neck brace early this morning, between 7.30 and 8.30.
The music mogul had an accident at his London home, according to The Sun.
Simon Cowell is currently in hospital undergoing tests but is in a stable condition, the publication claims.
A source said: “It’s been a scary morning. It was very early and Simon was going down his stairs to get some hot milk because he couldn’t sleep.
“He fainted and is thought to have fallen down the stairs.
“An ambulance was called and he was stretchered out of the house in a neck brace surrounded by worried aides.”
Spencer Sutherland shows off the results of his remarkable transformation [Instagram]
OK! Online has contacted representatives for Simon and The X Factor to provide a comment.
It is not known if his partner Lauren Silverman and their son Eric were at home at the time.
Simon is scheduled to appear on the first live shows of The X Factor tomorrow [Saturday 28 October].
It comes as excitement for the ITV programme reached a new level on Friday, after the show’s wildcard acts were announced.
What the contestants will be singing was also revealed.