Reports are that the rocker was suffering from stomach cramps and dehydration.
"We've had the curse of Download. Kid Rock is not very well, we've had to rush him to hospital. He apologizes to his fans," said a festival spokesperson.
What could have contributed to Kid's condition?
He was seen out partying at the Whisky Mist nightclub in London the night before.
He can rock and roll all night, but not party every day, it seems.
Kid's publicist has so far had no comment.
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