Ron Paul, the iconoclastic former Republican congressman from Texas who ran for president three times, attracting an enthusiastic following among libertarians, was hospitalized on Friday after he appeared to experience a medical episode and slurred his words while appearing on a livestream video.
Video posted on Twitter showed Mr. Paul talking about economics on his YouTube channel before his speech became unintelligible. The video was not available on his YouTube channel on Friday afternoon.
Shortly after, a photo shared on Mr. Paul’s Twitter account showed him smiling and giving the thumbs up from a hospital bed. “Message from Ron Paul: ‘I am doing fine. Thank you for your concern,’” the tweet said.
It was not immediately clear if Mr. Paul had experienced a stroke. Representatives for Mr. Paul and his son Senator Rand Paul, Republican of Kentucky, did not immediately respond to messages seeking information about his condition on Friday.
“Thank God, Dad is doing well,” Senator Paul said on Twitter. “Thank you for all your prayers today.”
Many other admirers of Mr. Paul expressed concern and wishes for his well-being on social media.
“Prayers for @RonPaul,” Representative Justin Amash of Michigan, a libertarian and former Republican, wrote on Twitter. “May God watch over him and his family.”
Senator Ted Cruz, Republican of Texas, wrote on Twitter that he and his wife, Heidi, were praying for Mr. Paul and his family.
“For many decades, he has been an extraordinary warrior for Liberty,” Mr. Cruz wrote.
A medical doctor trained in obstetrics and gynecology, Mr. Paul, 85, served in the House of Representatives over more than three decades, from 1976 to 1977, from 1979 to 1985 and again from 1997 to 2013.
Considered an outsider in the Republican caucus, he became a nationally known figure while running for president as the Libertarian nominee in 1988 and while campaigning unsuccessfully for the Republican presidential nomination in 2008 and 2012.
His views on fiscal policy — he is an unstinting critic of the Federal Reserve — and his staunch opposition to American military policy overseas won him legions of followers, especially among young and libertarian-leaning voters.
During his campaign for the Republican presidential nomination in 2008, he was best remembered for declaring in a debate that the Sept. 11 attacks were the Muslim world’s response to American military intervention around the globe. A fellow candidate, former Mayor Rudolph W. Giuliani of New York, interrupted and demanded that he take back the words. Mr. Paul refused.
During his years in Congress, Mr. Paul often staked out the lonely end of 434-to-1 votes against legislation that he considered unconstitutional, even on issues as ceremonial as granting Mother Teresa a Congressional Gold Medal. His colleagues nicknamed him “Dr. No.”
Although no one associated with Mr. Paul has given any details of his medical condition, there was broad speculation that he had a stroke, which occurs when a vessel in the brain ruptures or is blocked by a blood clot. Early signs of a stroke include slurred speech, face drooping and arm weakness, according to the American Stroke Association, which recommends calling 911 if a person shows any of these symptoms, even if they go away.
Immediate medical treatment is critical, the association says, because it can minimize the long-term effects of a stroke and prevent death.