Angus Cloud, the 25-year-old co-star of hit HBO drama "Euphoria," died from an accidental drug overdose in July, a US coroner said Thursday.

"Angus Cloud died from a lethal combination of fentanyl, cocaine, methamphetamine and benzodiazepine in what is ruled as an accidental overdose," a spokesperson for Alameda County Coroner's office in California told AFP.

"Angus suffered from acute intoxication from the combination of drugs."

A statement at the time of his death said Cloud, who portrayed laconic drug dealer Fezco "Fez" O'Neill in the multiple Emmy Award-winning series, had been struggling to deal with the recent passing of his father, and had experienced ongoing mental health issues.

"The only comfort we have is knowing Angus is now reunited with his dad, who was his best friend," said his family, in a statement sent by Cloud's publicist.

"Angus was open about his battle with mental health and we hope that his passing can be a reminder to others that they are not alone and should not fight this on their own in silence."

"Euphoria," fronted by star Zendaya, is one of the most-watched HBO series of all time.

The show has drawn controversy as well as plaudits for its dark depiction of the issues facing contemporary American teens, including drug addiction and sexual violence.

The gritty hit was Cloud's first acting job, having been discovered by a casting director while walking through the streets of Brooklyn, New York with friends.

"We hope the world remembers him for his humor, laughter and love for everyone. We ask for privacy at this time as we are still processing this devastating loss," said the family statement.