Bice, 30, became ill Sunday while rehearsing for a performance on the 2005 Radio Music Awards at the Aladdin Resort & Casino, said Roger Widynowski, a publicist for RCA Records.
"He didn't collapse but was rushed to the hospital," Widynowski said. "Bo is doing fine, and he's going back to Nashville today for treatment."
Bice was in Las Vegas with other "Idol" contestants in August when he underwent emergency surgery to repair a blocked intestine. The recovery time forced him to stop touring with the show.
The Goo Goo Dolls were to replace Bice in Monday night's live Radio Music Awards broadcast on NBC, said Carrie Simons, a spokeswoman for the network.
Bice finished second on last season's "Idol" behind Oklahoma native Carrie Underwood. He released his first album, "The Real Thing," last week.