Sylvester Stallone's son Sage died of heart disease, the Los Angeles County Coroner announced Thursday.

The 36-year-old eldest son of the action star died suddenly in July, with many speculating that prescription drugs might have caused his untimely demise. After a full autopsy and toxicology exam, it was determined that the major cause of death was atherosclerotic coronary artery disease. Small traces of Vicodin were also found in his system, but there was no indication that the drug had anything to do with his passing.

According to friends and family, the movie distributor lived an extremely unhealthy lifestyle filled with junk food, soda, and cigarettes. There have also been unconfirmed reports that Sage was diagnosed with a heart murmur in his childhood years.

Sage was laid to rest on July 21 in Los Angeles.

Keep your head up Sly!

Sylvester Stallone looked somber leaving his Beverly Hills office building yesterday, and we have to hand it to the actor for putting on a brave face in light of his eldest son Sage's sudden death in July at the age of 36.

While promoting his latest film The Expendables 2, the 66-year-old action star revealed to Jay Leno how he was coping with the loss. "When life hits you pretty hard you can go into a dark corner. Or you can say, 'Okay fine, I'm going to find something to focus on,' you have your children, your wife, you try and be supportive to other people too, because I know a lot of people go through [losing a child], and they don't get the attention that I do. And I feel for them, because it's one club that no one wants to be a member of, that's for sure. But I think about his memory, he was a lovely boy and I'll always treasure that," he explained to the talk show host.

What's that green bandage on your arm, Mr. Stallone? It looks like the bandaging they give you after you've had blood drawn, so hopefully it's nothing more than a routine test to make sure this Hollywood hunk is in tip top shape!

Sylvester Stallone, Jean-Claude Van Damme and Arnold Schwarzenegger joined their action co-stars at The Expendables 2 premiere in Hollywood.

The actors, who all put on their best suits and smiles, were happy to greet their adoring fans and pose for photos.

See all of the action studs hitting the red carpet in our gallery below.

Sylvester Stallone appeared on Good Morning America to promote his upcoming film The Expendables 2, when he addressed his 36-year-old son Sage's recent death for the first time.

While sitting alongside his action co-stars, Stallone told GMA:

"It's tough. It's very very tough. It's a horrible situation but, time, hopefully will heal and you try to get through it.

It's something that's a reality in life."

Sage Stallone was found dead at his California home on July 13.

It was a sad day for Sylvester Stallone, who led mourners at the private memorial for his son Sage at St. Martin of Tours Catholic Church in Brentwood, on Saturday afternoon.

The Rocky star was joined by close family and friends at the service and was accompanied by his current wife, Jennifer Flavin, ex-wife and Sage's mother Sasha Czack, younger brother Frank and longtime friend and attorney Marty Singer. Fans also gathered across the street from the church to show their support for Stallone.

After the service, the hearse was surrounded by a police motorcade as it was driven to Westwood Village Memorial Park Cemetery, where the 36-year-old will finally be laid to rest.

Sage was found dead in his home last Saturday of a suspected overdose, after bottles of pills were found scattered all over his room. Toxicology results are expected to be concluded within four to six weeks.

The cause of death for Sage Stallone will not be officially known for another two months, a spokesman for the Los Angeles County Coroner told CNN on Sunday evening.

The autopsy on Sylvester Stallone's 36-year-old son, who was found dead in his Los Angeles home of a suspected prescription pill overdose on Friday, was completed Sunday, but the Coroner's spokesman said it can take six weeks for toxicology tests to be completed.

Stallone was reportedly dead for several days before he was discovered by a housekeeper just before 3pm at his home in Studio City, and prescription pill bottles were found littered at the scene. It's also been reported that the actor was still alive through Sunday, and posted 17 pictures to his Facebook profile (like the one above) just hours before his body was discovered.

The Rocky star, who was at Comic-Con promoting The Expendables 2 when he received the news, released the statement through his rep: "Sylvester Stallone is devastated and grief-stricken over the sudden loss of his son Sage Stallone. His compassion and thoughts are with Sage's mother, Sasha. Sage was a very talented and wonderful young man. His loss will be felt forever."

Sage was planning to marry his longtime girlfriend in Las Vegas next weekend.

After Sylvester Stallone's son Sage was discovered unresponsive in his home in Studio City just shortly before 3pm on Friday afternoon, Assistant Chief Coroner Ed Winter arrived with police at the scene and confirmed the 36-year-old was dead.

No suicide note was found, Winter said, but prescription bottles were recovered from the home on Mulholland Drive, though Winter could not say what kind of medication bottles or how many, and no suicide note was found.

Winter said an autopsy will be performed within the next few days and while investigators will begin looking into Stallone's medical history, the toxicology tests will take several weeks to come back.

The Rocky actor was at Comic-Con in San Diego to promote Expendables 2 with co-star Arnold Schwarzenegger when he received the devastating news, saying in a statement through his publicist: "Sylvester Stallone is devastated and grief-stricken over the sudden loss of his son. His compassion and thoughts are with Sage's mother, Sasha."

George Braunstein, Stallone's attorney, said friends and acquaintances had become concerned about the 36-year-old when they hadn't heard from him in several days, and a housekeeper was the first to discover his body. It is believed that Sage had been dead for several days before being found, and was living in a room cluttered with trash which the staff was instructed never to enter.

Sage Moonblood Stallone was the oldest of Stallone's children with first wife Sasha Czack, and co-starred with his father in two films; 1990's Rocky V and 1996's Daylight.

These two went from former rivals to brunch buddies!

Over the weekend, cameras caught action stars Arnold Schwarzenegger And Sylvester Stallone as they teamed up for a manly breakfast at Cafe Roma in Beverly Hills.

Food isn't the only thing that's bringing these macho men together as the 64-year-old former Governor of California and Rocky star are joining forces again in The Expendables 2 and next year's prison trailer The Tomb. Now that's a lot of box office testosterone!