American television star Charlie Sheen has revealed he is HIV positive, following widespread speculation he was infected with the virus.

Speaking to American Today show host Matt Lauer, Sheen confirmed what multiple reports had already suggested: he tested positive for HIV (human immunodeficiency virus) four years ago and has been receiving treatment for it ever since.

What are HIV and AIDS? Read our explainer

Calm and collected and dressed in a suit and tie, Sheen declared: “I’m here to admit that I am in fact HIV positive.”

“I have to put a stop to this onslaught, this barrage, of attacks and sub-truths and very harmful and mercurial stories that are threatening the health of so many others – which couldn’t be farther from the truth,” Sheen explained of his decision to speak out.

Migraines and night sweats

Recounting his diagnosis, which took place “roughly four years ago”, Sheen said he originally thought he had a brain tumour.

“It started with what I thought – based on a series of cluster headaches, insane migraines, sweating the bed – I thought I had a brain tumour, I thought it was over.”

Sheen preparing for his live television interview.

Upon hearing the news, Sheen said he experienced a turning point in his life and initially resorted to “profound substance abuse” to cope.

“It’s a hard three letters to absorb. It’s a turning point in one’s life.”

‘We’re talking shakedowns’

Sheen went on to say he had been forced to pay off people who had discovered the news and threatened to tell the media.

This included a prostitute who photographed antiretroviral medication in his private bathroom in an effort to blackmail him.

“I’ve paid those people,” Sheen admitted to Lauer, who then asked exactly how many people Sheen had paid.

“Not that many,” Sheen responded. “I don’t want to guess wrong but enough to bring it into the millions [of dollars].

“What people forget is that’s money they’re taking from my children. they think it’s just me.

“For some reason I trusted them, they were deep in my inner circle, and I thought they could be helpful. My trust turned to their treason. We’re talking about shakedowns.”

Asked whether he would continue to pay these people, Sheen responded: “Not after today I’m not. That’s my goal.”

Possible transmission to others?

Sheen said it was “impossible” for him to have ever transmitted the virus – knowingly or otherwise – and said while he’d had unprotected sex since the diagnosis, his partners were warned ahead of time and under the care of Sheen’s doctor.

“Do you know how you contracted the virus?” Lauer asked.

“Sitting here today, not entirely, no,” Sheen responded.

Sheen’s doctor, Dr Robert Huizenga, also appeared on the show to explain that the levels of the virus in the actor’s system were barely detectable, making transmission “very rare”.

Matt Lauer (left) with Sheen (centre) and Dr Robert Huizenga.

“Charlie does not have AIDS. He is healthy,” Dr Huizenga said.

“[The medication has] suppressed the virus to the point where he is absolutely healthy to that vantage.”

However, Dr Huizenga said he was “petrified” about Sheen’s substance abuse and depression levels preventing him from taking his medication, although that hadn’t happened so far.

Hollywood’s worst-kept secret

Sheen’s HIV positive status was first publicly hinted at in an email sent to Sony executives leaked in a widespread hacking scandal and shared on Wikileaks.

The email, originally sent in March 2014 from an anonymous sender, included a link to a TV Week article detailing Sheen’s absence from filming on his short-lived sitcom Anger Management.

“It’s hard to to be a drug addict and be HIV positive and do 40 eps a year,” a message accompanying the link read.

This prompted the National Enquirer to then begin an 18-month investigation, uncovering what it described as “an open secret” in Hollywood.

According to the Enquirer, sources confirmed Sheen has been battling the illness for a number of years, with at least four women claiming he had exposed them to HIV.

Dylan Howard, editor-in-chief of the National Enquirer and Radar Online, told Australian radio station Kiis FM on Tuesday his publication was the reason Sheen decided to come forward.

“He’s only talking tomorrow because we went to him last week and told him we were about to publish an expose about how he had spent millions of dollars to cover up this deadly secret over the last four years by paying off women who have claimed that he infected them with HIV,” Howard said.

“I first learned about this two years ago, I’ve been investigating this for two years.

“I first confronted Charlie about this 18 months ago – at the time he threatened our publication with a $150 million lawsuit and said it was factually incorrect.

“We decided the victims in this … their interests far outweigh his,” Howard said of his publication’s decision to go ahead with the report.

The ex-wives and girlfriends

Sheen has been married and divorced three times and has boasted about sleeping with over 5000 women.

The actor has five children – one daughter with former girlfriend Paula Profit, two daughters with ex-wife Denise Richards and twin sons with ex-wife Brooke Mueller.

Sheen with ex-wife Denise Richards. Photo: Getty

According to PEOPLE magazine, Richards was aware of her ex-husband’s illness.

“She’s known Charlie was HIV positive for a number of years,” a source told the magazine of Richards.

“He was infected after they divorced [in 2006], and they haven’t been intimate since.

“Neither she nor their daughters [Sam, 11, and Lola, 9] are HIV positive.”

Mueller has allegedly provided a statement about the news to the Enquirer via text message, saying she feared her ex-husband had “potentially” infected her.

“I couldn’t handle the HIV news. Just 6 months ago I was diagnosed with the eye disease and then Charlie potentially giving me HIV…” she allegedly wrote.

Sheen with ex-girlfriend Natalie Kenly in 2011. Photo: Getty

On Tuesday, Sheen’s former girlfriend Natalie Kenly told PEOPLE she didn’t believe Sheen would intentionally infect his sexual partners.

“He has regard for human beings and cares about people. I do not see him knowingly putting women at risk,” Kenly said.

Bree Olson, another of Sheen’s former girlfriends, said she had been tested for the illness and alluded to Sheen’s diagnosis on Twitter.

“There are speculations circling that one of my ex-boyfriends from many years ago may have contracted the HIV virus,” Olson wrote.

“I, myself – have been to my gynaecologist at least once a year since we split up and have always been tested across the board for everything and have come back clean across the board every time.”

‘I told my daughter’

During his interview, Sheen also said he had told his eldest daughter Cassandra about his condition.

“I told my oldest daughter Cassandra the other night and – I felt bad – it hit her hard, but she recovered. She’s tough like her dad.”

What next?

In the state of California where Sheen resides, it’s illegal to intentionally pass on a sexually transmitted disease.

According to Radar Online executive editor Lachlan Cartwright, police sources have said they will be investigating the matter.

For Sheen to be charged, the state would have to prove he had knowingly infected women with the virus, using it “as a weapon”, health law expert Scott Burris told PEOPLE.

When asked by Lauer if he was concerned about more law suits and possible criminal charges in 35 states, Sheen said he could only “tell the truth” and hope for the best.

“Having divulged it is the reason I’m in the mess that I’m in … with all the shakedowns,” Sheen explained.

“I can only sit here with you and tell the truth.

“My financial situation is not great but I’m a survivor.”