Stan Rosenfield, Sheen's spokesman, told CNN the "Two and Half Men" star left Cedars-Sinai Medical Center Thursday night after being transported there by ambulance and admitted earlier in the day.
"Charlie has had a hernia condition for some time," Rosenfield said. "I was told by the person who made the 911 call that it was hernia-related."
The 45-year-old actor's successful career has long been marred by his legal woes, battles with drug and alcohol addiction, and failed marriages to Denise Richards and Brooke Mueller.
Some media reports said he was using cocaine and drinking heavily before his latest health crisis.
"He definitely did not OD but, yes, he was partying," an unidentified friend told People.com.
"He doesn't think he's going to die. He doesn't want to stop. In his eyes, he thinks: 'I'm having fun, so what? I'm making $2 million a week, the show has the best ratings, I show up for up work. What's the problem?'" the friend said.
Sheen's spokesman told UsMagazine.com the actor "voluntarily entered an undisclosed rehabilitation center."
"He is most grateful to all who have expressed their concern," his representative told UsMagazine.com.
Although Sheen was expected to return to work Tuesday, the show's producers said the series is now on break.
"Due to Charlie Sheen's decision to enter a rehabilitation center, CBS, Warner Bros. Television and executive producer Chuck Lorre are placing 'Two and a Half Men' on production hiatus," a statement released by the makers of the show said Friday. "We are profoundly concerned for his health and well-being, and support his decision."