The official finding was released Tuesday, more than a month after the 36-year-old actress was found unresponsive at a residence in Greenville on August 16.
According to The Associated Press, the coroner determined that Panettiere died from the toxic effects of fentanyl along with other drugs found in her system. Her death was ruled accidental.
The Greenville County Coroner’s Office listed fentanyl, 4-ANPP, alprazolam, methocarbamol and quetiapine as substances involved in her death. Alprazolam is commonly sold under the brand name Xanax. Methocarbamol is a muscle relaxant while quetiapine is a prescription medication used to treat several mental health conditions.
Emergency responders were called to a Greenville residence at 1:51 p.m. on August 16 after receiving a report of a cardiac arrest.
Panettiere was found unresponsive. Paramedics began advanced cardiac life support measures but were unable to revive her. She was pronounced dead at 2:32 p.m.
An autopsy was performed the following day. Officials initially said there were no signs of trauma that contributed to her death. The Greenville Police Department also said there was no evidence of foul play.
For several weeks, the official cause of death remained pending while investigators waited for toxicology testing.
The coroner’s office cautioned earlier this month that reports claiming to know the cause of death were premature.
On September 14, the office told FOX Carolina that it had not yet released an official cause or manner of death and that the investigation remained open while toxicology results were being completed.
Tuesday’s announcement provided the first official determination from the coroner.
Panettiere became one of Hollywood’s most recognizable young actresses after beginning her career as a child.
She appeared in the 2000 football drama “Remember the Titans” alongside Denzel Washington. She played Sheryl Yoast, the football-loving daughter of assistant coach Bill Yoast.
Panettiere later became widely known for playing Claire Bennet on the NBC series “Heroes.” Her character was a cheerleader who discovered that she had the ability to heal from serious injuries.
She also starred as country singer Juliette Barnes on the television drama “Nashville.” The performance earned her two Golden Globe nominations.
Her film credits included “Racing Stripes,” “Ice Princess,” “Scream 4” and “Scream VI.”
Panettiere had spoken publicly for years about struggles with alcohol and substance abuse.
She also discussed postpartum depression after the birth of her daughter Kaya in 2014.
In interviews and in her memoir, Panettiere described entering treatment while working on “Nashville” and said her addiction had affected both her career and personal life.
Her younger brother, actor Jansen Panettiere, died in 2023 at age 28. His family later said his death was caused by an enlarged heart.
Panettiere released a memoir in 2026 in which she discussed childhood fame, addiction, motherhood and several difficult periods in her life.
She was just days away from her 37th birthday when she died.
Panettiere is survived by her daughter Kaya, whom she had with former professional boxer Wladimir Klitschko.
The Greenville Police Department has continued investigating the circumstances surrounding her death even though the coroner has now officially ruled the death accidental.