Sage Stallone, the son of actor Sylvester Stallone, died of a heart attack and a toxicology report showed no signs of excessive drug use, an official with the Los Angeles County Coroner said on Thursday.

Stallone, who died at age 36 on July 13, suffered from coronary heart disease caused by atherosclerosis, which brought on the heart attack, Lt. Fred Corral of the coroner's investigative division said.

"There were no signs of an overdose. It was just a natural death," Corral said.

Stallone had a small amount of the sedative hydrocodone in his body, Corral said, but it was an acceptable level and one that could be found from taking over-the-counter pain medication. No other drugs surfaced in the toxicology report.

Sage Stallone's body was found in his Hollywood Hills home after family and friends became concerned when they hadn't heard from him for a day. A housekeeper went to check, found his body and called police, according to his lawyer, George Braunstein.

At the time, police said there was no sign of foul play, but speculation quickly surfaced in the tabloid media of a possible drug overdose.

Sage Stallone was the younger of two sons from the "Rocky" and "Rambo" actor's first marriage to Sasha Czack, whom he divorced in 1985 after about 10 years of marriage.

He had appeared in a number of films, most notably with his father in 1990's "Rocky V," playing the title character's son, Rocky Balboa Jr., and in the 1996 disaster movie "Daylight," in which Sylvester Stallone starred as a hero leading an escape from a New York tunnel collapse. Sage played a prison inmate.

Sylvester Stallone, 66, has not been seen much in public since his son's death, even as his new movie, "The Expendables 2," landed in theaters.

On Thursday, his spokeswoman said the actor had no comment.

The Oscar-winning actor gave a recent interview to the ABC News show "Good Morning America" in which he said: "Time, hopefully, will heal, and you try to get through it, but it's just something. It's a reality of life."