He was said to be close to death last year as he allegedly battled a devastating heroin addiction.
But he managed to clean himself up, and now it seems Macaulay Culkin has replaced drugs with another dangerous habit.
The 32-year-old is said to be smoking a whopping 60 cigarettes a day, leading to new health fears for the troubled former child star.
Dangerous habit: Macaulay Culkin, pictured in 2010 in New York, is said to be smoking 60 cigarettes a day, leading to fears that he may contract lung cancer, reports the National Enquirer
Sickly: The 32-year-old made headlines in February last year when he was pictured looking alarmingly thin
'He's put his nicotine addiction into overdrive,' a source told the National Enquirer. 'Almost every time I see him, he has a cigarette dangling from his lips and is puffing furiously.'
The effects of his unhealthy habit are starting to show, said another source.
'He's coughing a lot, his teeth are yellowing, and friends and family are worried he's killing himself.'
Experts tell the publication that the actor's addiction puts him at serious risk of contracting lung cancer.
Jerome Spunberg, a radiation oncologist in Palm Beach Gardens, Florida, (who has not treated the star) told the National Enquirer that Macaulay has '30 times the risk' of dying from the disease than someone who doesn't smoke.
Another doctor, Herman Kattlove, former spokesperson for the American Cancer Society, said Macaulay's lung cancer risk will 'eventually exceed 100 times that of a nonsmoker.'
Macualay is also chugging cognac, beer and energy drinks, say insiders.
Sources say his recent troubles are as a result of a recent breakup with an ex-stripper girlfriend, and he also had a run-in with a photographer outside a nightclub in Brighton, UK.
'All of this has Mac very stressed out, and that causes him to smoke more,' said a friend.
MailOnline reached out to Macaulay's rep for comment but did not receive any response.
Last August, The National Enquirer reported that Macaulay had a $6000-a-month drug habit and that he was hooked on 'hillbilly heroin.'
But a spokeswoman for the actor branded the claims published in the National Enquirer as 'ridiculously fictitious' and 'insulting'.
Troubled: The former child star, pictured in April in London, is said to also be chugging cognac, beer and energy drinks
The National Enquirer, however, issued a statement to say they were firmly standing by their story.
A source told the publication: 'Macaulay Culkin is hooked on drugs and it's killing him.
'He's been hooked for a year and a half, and his drug of choice is either heroin or oxycodone.
The source - described by the Enquirer as a 'close friend' - also claimed Macaulay has had a close brush with death in the past year and almost overdosed.
'Mac suffered a near overdose, and needed help,' the insider said.
Macaulay's half sister Jennifer Adamson died of a drug overdose in 2000.
Child star: Macauley is best known for his role as cheeky Kevin McCallister in the 1992 film Home Alone
Macaulay is best known for his roles as cheeky Kevin McCallister in the 1990 film Home Alone and the 1992 sequel, Home Alone: Lost In New York.
He also starred in the likes of Uncle Buck, My Girl and Richie Rich.
But his adult career has failed to match the blockbuster success of his childhood days.
In 2003 he played a drug-addled club hopper alongside Seth Green in Party Monster, while his last film role was in 2007 in the Indie flick Sex And Breakfast.
These days he earns a living deejaying at clubs around New York.