Photo: © 2010 AAP/Warner Bros
The child star turned drug abuser collapsed in his mother's apartment in Burbank, California, and was pronounced dead before reaching hospital.
At the time of his death, Haim was taking prescription drugs for the flu-like symptoms he was suffering.
His agent has denied rumours the death was the result of an overdose.
"Corey was actually going very clean in his life," Mark Heaslip told CNN.
Investigators have confidently ruled out foul play, finding no illegal drugs in the apartment.
Haim had a history of drug abuse – including cannabis, cocaine and crack – and once revealed he'd taken up to 85 hits of valium during one of his 15 rehabilitation attempts.
In 1997, he filed for bankruptcy.
Former co-star and friend, Corey Feldman, described Haim as a "wonderful, beautiful, tormented soul".
Ex-girlfriend Alyssa Milano has also paid tribute to her "sweet boy".
An autopsy is yet to confirm the cause of death.
