Charlie Sheen is expected to announce that he is HIV positive in an exclusive TV interview.
NBC said in a statement that Sheen, 50, would make a "revealing personal announcement" in a live interview on its morning Today show.
NBC did not give details of the interview, but Celebrity website TMZ, citing sources close to the Today show, said Sheen would use the interview to announce that he is HIV positive.
Sheen's representatives could not be reached for comment, and Reuters was not able to verify reports on the state of his health.
The National Enquirer tabloid reported on Monday following an 18-month long investigation that Sheen was diagnosed HIV positive some years ago.
Sheen quickly became one of the top 10 worldwide trends on Twitter on Monday, and Google searches for his name associated with HIV exploded, according to Google.
Sheen played the womanising bachelor Charlie Harper on top-rated comedy Two and A Half Men for eight years before being fired in 2011 for bad behaviour that included cocaine-fuelled partying with porn stars and a conviction for assaulting his ex-wife.
The three times divorced Sheen then set up home with a number of porn stars he called "goddesses" and delivered a series of rants on YouTube boasting of having "tiger blood" in his veins.
Sheen, the son of West Wing actor Martin Sheen, starred in the TV comedy Anger Management, which was closely based on his life, from 2012-2014.
