Sage Stallone (far right) seen here with Sylvester Stallone and Jennifer Flavin Stallone
Los Angeles (CNN) -- Sage Stallone, the 36-year-old son of actor Sylvester Stallone, died of atherosclerosis, which brought on a heart attack, a spokesman for the Los Angeles County coroner said Thursday.
Stallone was found dead in his Los Angeles home on July 13 by his housekeeper, who was asked by Stallone's mother to check on him.
No drugs were found in Stallone's body other than an over-the-counter Tylenol-style pain medication, according to Lt. Fred Corral of the coroner's office.
Stallone's family was recently notified of the findings, which will be detailed in a full autopsy report to be made public next week, Corral said.
Sylvester Stallone made a public appeal last month for an end to "speculation and questionable reporting" about his son using drugs.
"Because when a parent loses a child there is no greater pain," Stallone said. "Therefore I am imploring people to respect my wonderfully talented son's memory and feel compassion for his loving mother, Sasha, because this agonizing loss will be felt for the rest of our lives. Sage was our first child and the center of our universe and I am humbly begging for all to have my son's memory and soul left in peace."
Sudden celebrity deaths often draw early speculation about drug involvement in Hollywood, but in several recent cases the cause of death proved to be natural.
Although the investigation into actor Corey Haim's death two years ago began as a "suspected prescription medication overdose," toxicology tests "revealed no significant contributing factors" from drugs, the coroner later concluded. Pneumonia, not drug abuse, killed Haim.
Similar speculation about drug use followed the December 2009 death of actress Brittany Murphy. The coroner eventually ruled that Murphy died from a combination of pneumonia, an iron deficiency and multiple drug intoxication. The drugs involved are legal and are used to treat respiratory infections, according to the autopsy report.
Stallone was engaged to be married and was working on various film projects at the time of his death.
He acted in several movies, including "Daylight" and "Rocky V" with his father.
The younger Stallone also co-founded Grindhouse Releasing, a company that describes itself as "dedicated to the restoration and preservation of motion pictures historically held in very low regard."
CNN's Douglas Hyde contributed to this report.