Heroes star Hayden Panettiere died from 'toxic' mix of drugs, including fentanyl: coroner's report

An image of Hayden Panettiere appears during the in memoriam presentation at the Emmy Awards on Sept. 14 in Los Angeles. A South Carolina coroner's office has released the cause of death for the Heroes and Nashville star. (Chris Pizzello/Associated Press)Social SharingThe recent death of Hayden Panettiere has been ruled accidental and attributed to "toxic effects" of a mix of drugs, including fentanyl, according to the Greenville County Coroner's Office.

The actor, known for roles in TV shows like Heroes and Nashville, died on Aug. 16 at a Greenville, S.C., residence where she'd been staying.

Upon arriving at the scene, emergency responders had found Panettiere in cardiac arrest and were unsuccessful with their resuscitation efforts, according to the office.

Following a joint investigation by the office alongside the Greenville City Police Department, "the cause of death has been ruled as toxic effects of fentanyl, 4-ANPP, Alprazolam, Methocarbamol, and Quetiapine," the office confirmed to CBC News in an official statement on Tuesday.

Quetiapine is an antipsychotic medication used to treat schizophrenia, bipolar disorder and major depression and Alprazolam is used to treat anxiety and panic disorders as well as anxiety caused by depression.

Methocarbamol is a muscle relaxant, while 4-ANPP is a compound linked to the production of fentanyl, a powerful opioid.

During the autopsy, "no signs of trauma were discovered that would have contributed to the death," the statement added.

The television and film performer, who died days ahead of her 37th birthday, had openly discussed personal struggles with early fame, addiction and mental health, including postpartum depression following the birth of her daughter in 2014.

Panettiere spoke and wrote candidly about her life, including in interviews and in her recent memoir, This Is Me: A Reckoning.

Her death unleashed a flood of tributes and remembrances from co-stars and fans.

Why are people mad at Neutrogena on behalf of Hayden Panettiere?

It also revived an earlier backlash against skincare company Neutrogena, for whom Panettiere had served as a global brand ambassador and pitchwoman for nearly a decade before the birth of her daughter.

She had alleged the company dropped her after she began speaking openly about her struggle with postpartum depression.