According to a person familiar with the emergency call placed on Thursday (local time), one of Sheen's neighbours told a 911 operator that the actor was "intoxicated" and complaining of abdominal and chest pains.
The person familiar with the call, who was not authorised to publicly discuss details, spoke on condition of anonymity. Copies of the call probably won't be ready for release by the Los Angeles Fire Department until Monday, a department spokesman said.
Sheen, 45, was taken to a Los Angeles area hospital and was there until around midnight on Thursday, said his publicist, Stan Rosenfield, who cited the actor's history of hernia problems.
Rosenfield said that Sheen was in rehab, but he did not say why.
"Charlie Sheen has voluntarily entered an undisclosed rehabilitation centre today," the spokesman said. "He is most grateful to all who have expressed their concern."
The terse statement noted that no additional information will be provided and asked that Sheen's privacy be respected.
CBS, production company Warner Bros. Television and executive producer Chuck Lorre said in a joint statement that Sheen's rehab has prompted a halt on production of "Two and a Half Men."
"We are profoundly concerned for his health and well-being, and support his decision," the companies and Lorre said.
Sixteen of the show's 24-episode order have been taped, with 14 aired so far.
The latest fallout from Sheen's chaotic life came two weeks after CBS' top entertainment executive said the actor's off-camera actions haven't affected his work as the star of TV's most popular comedy, the centerpiece of CBS' Monday comedy lineup.
Sheen's headline-making behaviur has included a wild night that left a New York hotel room in shambles and sent him to a hospital, and a guilty plea last summer to assaulting his wife in Aspen, Colorado. Sheen filled gossip pages again this month by spending a weekend partying in Las Vegas.
His latest hospitalisation was his third in as many months. It came after a 911 call made on Sheen's behalf by neighbour Dr Paul Nassif. The plastic and reconstructive surgeon, along with his wife Adrienne Maloof-Nassif, are in the reality show "The Real Housewives of Beverly Hills."
Last February, Sheen entered rehab for an unspecified problem, forcing his sitcom to temporarily suspend production.
Earlier this month, CBS Entertainment President Nina Tassler was asked about Sheen at a news conference with TV reporters.
"We have a high level of concern. How can we not?" she said, adding the situation can't be viewed simplistically. The actor does his job on "Two and a Half Men" reliably well, she said.
When a questioner suggested a person in a different line of work would be fired for involvement in similar incidents, Tassler replied, "What do you get fired for? Going to work and doing your job?"
Sheen's Monday night programme has increased its audience by 2 percent over last season, the Nielsen Co. said. He signed a new two-year contract at the end of last season that makes him one of the highest-paid actors on prime-time television.
