Though a full coroner's report won't be released for some time, Corey Haim's mother told Access Hollywood that he died of an enlarged heart and fluid in his lungs.
Corey Feldman: Haim was "in the best frame of mind that he's ever been"
Judy Haim said she received a call from the Los Angeles County coroner's office letting her know her son's cause of death.
Haim, 38, was taken to a Burbank hospital where he was pronounced dead Wednesday.
See photos of child stars gone too soon
His friend and recurring co-star, Corey Feldman, acknowledged on Larry King Live that Haim had struggled with addiction for many years, but urged the public not to jump to conclusions until a full report was released.
The coroner's office did not immediately respond to TVGuide.com's request for comment.