Charlie Sheen and Tom Sizemore. (File photos)

Actor Tom Sizemore is reaching out in a bid to help troubled star Charlie Sheen seek help.

Black Hawk Down star Sizemore fears his old pal will die if he doesn't get the counselling he needs, and he's hoping that the actor will see sense as he tries to help him get his life in order.

Sizemore tells CNN, "I don't want to be a doomsayer, but if he doesn't get any help it's just going to get worse.

"He could have a crippling heart attack and not die and be a vegetable. He could die... There's been a series of events here that are very, very worrisome."

Sizemore is referring to Sheen's Christmas Day fight with his wife Brooke Mueller in Aspen, Colorado, which landed the star behind bars and his reported hotel room meltdown in New York last month.

Sheen underwent rehab earlier this year following his assault conviction, but he has never spoken about drink or drug-related issues.

Sizemore, who has spent much of the last decade battling his own substance abuse problems, tells CNN he thinks Sheen is in denial, and he wants the troubled star to get help like he did.