The effects of fentanyl were the cause of death for Adam Rich, the child actor known as “America’s little brother” for his role on the family dramedy Eight Is Enough, a coroner has ruled.

The former television star’s death this January was ruled to be an accident by the Los Angeles County Medical-Examiner Coroner’s office, according to a post-mortem report.

Rich died in his Los Angeles home aged 54.

His stardom came at just eight years old as the mop-topped son raised by a widower newspaper columnist in ABC’s Eight Is Enough.

A limited acting career followed the show’s run from 1977 to 1981.

Rich had publicly discussed his experiences with depression and substance abuse in the months before he died.

He tweeted in October that he had been sober for seven years after arrests, many rehab stints and several overdoses. He urged his followers to never give up.

He was arrested in April 1991 for trying to break into a pharmacy and again that October for allegedly stealing a drug-filled syringe at a hospital while receiving treatment for a dislocated shoulder.

A drink-driving arrest came in 2002 after he struck a parked California Highway Patrol cruiser in a closed freeway lane.