A hospital spokeswoman said the singer was in stable condition. McCready attorney Lee Ofman said he did not have details about the situation and her publicist did not immediately return a phone message early Thursday.
McCready, who had a No. 1 hit in 1996 with "Guys Do It All the Time," has struggled in recent years with legal and personal problems that included previous suicide attempts.
In October, the 33-year-old was released from jail in Tennessee after serving about 30 days for violating probation on a 2004 drug charge. She only had to serve about half of her 60-day sentence because of credits she received for good behavior and doing janitorial work in the jail, the Williamson County Sheriff's Department said.
She was accused in June of falsifying her community service records and charged with violating her probation. McCready received a suspended three-year sentence in 2004 for fraudulently obtaining prescription painkillers.
The country singer has also made headlines because of her relationship with former baseball star Roger Clemens.
According to an interview broadcast in November by the syndicated show "Inside Edition," McCready claimed she broke off her relationship with Clemens when he wouldn't marry her.
McCready, however, was quoted the same day on the Web site of the New York Daily News as saying she didn't want to marry Clemens.
McCready told "Inside Edition" she met Clemens when she was 16, not 15, as reported by the New York Daily News last April. She told the news magazine they met in a karaoke bar, that her relationship with the pitcher didn't turn sexual until several years later and the relationship lasted for a decade.
"Carrying on a relationship with him is not something I'm proud of," she said, according to a partial transcript released by the show. "Roger Clemens is one of the most wonderful men I've ever known. ... He treated me like a princess."
Clemens in May denied having an affair with a 15-year-old but didn't specifically address whether he had a romance with McCready.