"You know I have always tried to be honest with you and open about my life," Limbaugh said Friday on his program. "So I need to tell you today that part of what you have heard and read is correct. I am addicted to prescription pain medication."
Limbaugh said he began taking the medication "some years ago" when his doctor prescribed it after spinal surgery, to treat post-operation pain.
But the operation was unsuccessful and the back pain stemming from the surgery persisted, so Limbaugh said he started taking pills without knowing how addictive they were. He became hooked.
He said he's tried to break his dependence on the painkiller and twice checked himself into medical facilities for treatment.
Limbaugh promised listeners he would again enter rehab for the next 30 days, immediately following Friday's broadcast, "to once and for all break the hold this highly addictive medication has on me."
He didn't mention what specific painkiller he was hooked on. Limbaugh said his show would continue with guest hosts filling in until he could return to work.
A spokesman for Premiere Radio Networks (search), which syndicates the politically focused "Rush Limbaugh Show (search)" to more than 650 markets, said Limbaugh is expected to return to his program after completing rehab.
But Premiere spokesman Michael Sitrick declined to elaborate on Limbaugh's previous treatment.
One media analyst said Limbaugh had no choice but to come clean and confess.
"He had painted himself into a corner," said Matthew Felling, media director at the Center for Media and Public Affairs. "You cannot be a public personality demanding accountability of everyone on the face of the earth and hide behind legalese."
As for how the news will be received by Limbaugh's fans, Felling said that remains to be seen.
"Now that his public persona has admitted weakness and personal failing, it will be interesting to see how his red meat audience responds," said Felling. "To humanize him may de-fang him to a certain degree."
The radio commentator had already been cited as a possible target of a criminal probe into the sale and use of illegal drugs.
Limbaugh, who quit his job as a football analyst for ESPN Oct.1, had multiple sources from whom he could obtain the prescription drugs, namely OxyContin (search) and other painkillers, law enforcement sources said last week.
Reports in the New York Daily News and the National Enquirer alleged Limbaugh got the drugs from his housekeeper, Wilma Cline (search).
"I've spoken with the clients and they are pleased that the publication of this story has possibly had the effect of saving Rush Limbaugh's life," Edward Shohat, attorney for Wilma and David Cline, told Fox News in reaction to Limbaugh's admission. "The exercise of First Amendment rights can have very positive effects."
Last week, sources close to the investigation told Fox News that Limbaugh had other drug suppliers apart from Cline and said the popular conservative personality could face a criminal inquiry by the Palm Beach County (search) state attorney's office.
Limbaugh acknowledged the drug probe on Friday.
"At the present time, the authorities are conducting an investigation, and I have been asked to limit my public comments until this investigation is complete," Limbaugh said on his program, adding that there had been inaccuracies reported and he would clear them up when he was allowed to speak about the investigation.
Steve Plamann, executive editor of The National Enquirer, said he was gratified by Limbaugh's admission and his plans to seek help.
"We didn't do our stories gleefully. We just reported the facts," Plamann said.
Friday's admission was the latest development in an ongoing scandal that has surrounded the talk show host, known for his bluntness and controversial political views.
Limbaugh resigned as ESPN's football analyst after outrage spread over his comment that Philadelphia Eagles quarterback Donovan McNabb, who is African American, had become a media darling because he is black.
He said on the Sept. 28 edition of ESPN's "Sunday NFL Countdown" that McNabb was overrated because the press wanted to see a black quarterback succeed.
"I think what we've had here is a little social concern in the NFL. The media has been very desirous that a black quarterback do well," Limbaugh said then. "There is a little hope invested in McNabb, and he got a lot of credit for the performance of this team that he didn't deserve. The defense carried this team."
Later he apologized for making people uncomfortable but stood by his comments.
Limbaugh's opponents will likely call him a hypocrite after Friday's confession, since he has criticized crack addicts in the past and said drug offenders should be thrown in jail like any other criminals.
In the past, Limbaugh has decried drug use and abuse on his bluntly conservative show, mocking President Bill Clinton for not inhaling and often making the case that drug crimes deserve punishment.
"Drug use, some might say, is destroying this country. And we have laws against selling drugs, pushing drugs, using drugs, importing drugs. ... And so if people are violating the law by doing drugs, they ought to be accused and they ought to be convicted and they ought to be sent up," Limbaugh said on his short-lived television show on Oct. 5, 1995.
During the same show, he commented that the statistics that show blacks go to prison more often than whites for the same drug offenses only illustrate that "too many whites are getting away with drug use."
But Felling of the Center for Media and Public Affairs said he doubted Limbaugh's career would tank because of his acknowledgment.
"I'm not willing to write his media obituary yet," said Felling. "He has proven a very durable personality."
When Limbaugh admitted the drug problem on his program, he said he wasn't a victim and didn't want to be portrayed as such.
"I am no role model," the radio commentator said. "I refuse to let anyone think I am doing something great here ... I take full responsibility for my problem."
OxyContin is a narcotic painkiller that is widely prescribed for victims of moderate to severe chronic pain resulting from such problems as arthritis, back trouble and cancer.
Limbaugh reported two years ago that he had lost most of his hearing because of an autoimmune inner-ear disease. He had surgery to have an electronic device placed in his skull to restore his hearing.
Research has found that abuse of opiate-based painkillers like OxyContin can lead to profound hearing loss caused by damage to the inner ear, said Dr. Gail Ishiyama, an assistant professor at the UCLA department of neurology. She could not confirm that was Limbaugh's case without access to his medical history.
The Associated Press contributed to this report.