Los Angeles, California (CNN) -- The autopsy on Corey Haim revealed the actor's heart was enlarged and his lungs were filled with water when he died, Haim's manager said.
The Los Angeles County coroner told Haim's mother that her son suffered from pulmonary congestion, manager Mark Heaslip said.
Heaslip said this was evidence that Haim's death was not caused by a drug overdose, but Brian Elias with the coroner's office said they are waiting for toxicology tests before deciding what killed Haim.
The 1980s teen movie actor, who struggled for decades with drug addiction, died early Wednesday after collapsing in the Los Angeles apartment he shared with his mother, authorities said.
Longtime friend and frequent co-star Corey Feldman asked Wednesday that people not "jump the gun" to conclude a drug overdose killed Haim.
Heaslip, manager to both Feldman and Haim, said he seemed to be winning his battle against drug abuse in the weeks before his death.
Haim, 38, was taken to Providence St. Joseph Medical Center in Burbank, California, early Wednesday, where he was pronounced dead at 2:15 a.m. PT (5:15 a.m. ET), said Ed Winter, Los Angeles County deputy coroner.
Haim was in the apartment he shared with his mother, Judy Haim, when he "became a little dizzy, he kind of went to his knees in the bedroom," Winter said. "His mom assisted him in the bed. He became unresponsive."
His mother called paramedics to the apartment, which is between Hollywood Hills and Burbank, he said.
Haim had suffered from flulike symptoms for two days, the deputy coroner said.
"We found no illicit drugs. However, we did recover four of his prescription meds at the location," Winter said, adding he does not know what those drugs were.
Haim was "weaned down to literally zero medications" in the past two weeks by an addiction specialist, Heaslip said on HLN's "Issues With Jane Velez-Mitchell" on Wednesday.
The doctor "put him on a new line of medications," Feldman said on CNN's "Larry King Live" on Wednesday.
Feldman pleaded with people not to draw conclusions that Haim died from a drug overdose. He said that until the autopsy report is issued, "nobody knows and nobody's going to know."
"I know that there were symptoms that he was showing that expressed it could be a number of things," Feldman said. "This could have been a kidney failure. This could have been a heart failure."
Heaslip that said Haim's mother, Judy, told him "there were no signs of him overdosing."
His death came as his career was picking up, with Haim booking "movie after movie," Heaslip said. His latest film is set for release soon, he said.
Haim "really became a man" in recent months as he helped his mother in her battle with cancer, Feldman said. "He's been there for her, taking care of her, being responsible," he said.
Feldman said he was angry about how Haim has been snubbed in recent years by the entertainment industry. He was broke, without a car and living in a month-to-month rental apartment with his mother, he said.
"We build people up as children, we put them on pedestals and then when we decide that they are not marketable anymore, we walk away from them," he said.
Haim's most famous role was in the 1987 movie "The Lost Boys," in which he appeared with Feldman. Haim played the role of a fresh-faced teenager whose brother becomes a vampire.
In later years, the two friends -- who appeared in eight movies together -- struggled with drug abuse and went their separate ways. They reunited for a reality show, "The Two Coreys," in 2007, but A&E Network canceled the program after slightly more than a year.
In a 2007 interview on CNN's "Larry King Live," Haim and Feldman discussed their battle with drugs. Feldman told King that he had gotten clean, but it took Haim longer.
Haim called himself "a chronic relapser for the rest of my life."
"I think I have an addiction to pretty much everything," he said. "I mean, I have to be very careful with myself as far as that goes, which is why I have a support group around me consistently."
In 2008, Feldman told People magazine that he would no longer speak to Haim until his former co-star got sober. In a clip from "The Two Coreys," Feldman and his wife, along with two other former teen stars, called on Haim in an effort to get him to admit he needed help, the magazine said.
The meeting followed an incident in which Haim, scheduled to film a cameo appearance in a direct-to-DVD sequel to "The Lost Boys," appeared on the set "clearly under the influence," People reported.
Feldman told King on Wednesday that he renewed his contact with Haim in the past year because of the progress he made against his addiction.
Haim was born December 23, 1971, in Toronto, Ontario, according to a biography on his Web site. He made his first television appearance in 1982 on the Canadian series "The Edison Twins." His first film role was in the 1984 movie "First Born."
Haim also won rave reviews for his title role in the 1986 film "Lucas." Film critic Roger Ebert said of him at the time, "If he continues to act this well, he will never become a half-forgotten child star, but will continue to grow into an important actor."
Following "The Lost Boys," Haim and Feldman appeared in "License to Drive" and "Dream a Little Dream."
CNN's Brittany Kaplan contributed to this report.