Harrison Wagner, whose father, Jack Wagner, was known for his role on "General Hospital," died from "fentanyl and alprazolam intoxication," according to the Los Angeles County Medical Examiner-Coroner.
His death in June was listed as an "accident" in the coroner's report. Xanax is a common brand name for alprazolam.
Earlier this year, Wagner and ex-wife Kristina founded The Harrison Wagner Scholarship Fund to honor their late son by helping others who struggle with addiction.
The former "General Hospital" co-stars described their son as "a bright, exuberant young man whose smile lit up any room he was in."
‘GENERAL HOSPITAL’ SOAP STAR JACK WAGNER'S SON HARRISON, 27, FOUND DEAD IN LOS ANGELES PARKING LOT
"He has left behind many men and family members who loved him deeply," a statement on the fund’s website says.
JACK AND KRISTINA WAGNER SET UP SCHOLARSHIP IN SON'S NAME TO HELP PEOPLE STRUGGLING WITH ADDICTION
"We are heartbroken that he ultimately lost his battle with addiction and we hope that Harrison's memory will live on through this scholarship and will help other young men get help for their addiction that would not otherwise be able to afford it."
On Dec. 1, Kristina shared a somber post dedicated to her son on what would have been Harrison's 28th birthday.
"Sometimes I feel like a pinned butterfly. There’s no second chance. There’s no see-him-again. There’s no nothing. He’s not coming back. It’s final. But life goes on," she wrote. "How do I spend the rest of my own without Harrison in it? What does it mean to be ‘all right’ after the death of your child, your blood? The pain will never go away.
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"Today is Harrison’s birthdate. I had the privilege to know him for 27 incredible years. Harrison was larger than life, but beneath his commanding presence was vulnerability and compassion. He understood his own defects and worked hard to turn them around, to strengthen his positive attributes. He was a good listener and stood up for others when they couldn’t speak for themselves. He is missed. Happy Birthday, Harrison. To all bereaved parents: May you find peace. Let’s stick around and see what’s in store for our extraordinary lives."
Harrison was pronounced dead at the scene at 5:14 a.m. in the 11200 block of Chandler Boulevard in the San Fernando Valley suburb of North Hollywood on June 6. His initial cause of death was currently listed as "deferred."
The coroner's office told Fox News Digital: "Deferred means that after an autopsy, a cause of death has not been determined and the medical examiner is requesting more investigation into the death, including additional studies. Once the tests/studies come back, the doctor evaluates the case again and makes the cause of death determination."
Jack and Kristina were married for 13 years before their divorce was finalized in 2006. They also have a son named Peter, and Jack has a daughter, Kerry, from another relationship.
Following Jack's divorce, he was in a longtime romance with Heather Locklear beginning in 2007.
The couple, who worked together on "Melrose Place" in the '90s, became engaged in 2011 but called off their nuptials only three months later. She was previously married to Bon Jovi guitarist Richie Sambora.