Cause of death of actress Hayden Panettiere revealed

American actress Hayden Panettiere, known for the series "Heroes" and "Nashville," died from the toxic effects of fentanyl and several other drugs. The coroner's office ruled her death an accident.

This was reported by NBC News, citing the Greenville County coroner's office in South Carolina.

According to the toxicology report, the cause of death was the toxic effects of fentanyl, 4-ANPP, alprazolam, methocarbamol, and quetiapine.

4-ANPP is a substance related to fentanyl production. Alprazolam is used to treat anxiety disorders, methocarbamol is a muscle relaxant, and quetiapine is an antipsychotic medication.

The autopsy found no injuries that could have caused the actress's death. After determining the cause and manner of death, the coroner's office administratively closed its part of the investigation.

Panettiere died on August 16, 2026, at age 36—just days before her 37th birthday. She was found unconscious in an apartment in Greenville, where she was temporarily staying. After a call for cardiac arrest, medics attempted resuscitation, but were unable to save the actress.

According to FOX Carolina, the Greenville police are continuing a separate investigation into the circumstances of the death. Earlier, law enforcement reported that no signs of violent death were found.

Panettiere had openly discussed her struggles with addiction and treatment. A few weeks before her death, she was in a rehabilitation center.

Hayden Panettiere rose to fame for her role as Claire Bennet in the series "Heroes," and later starred in the musical drama "Nashville." She also appeared in films such as "Scream 4," "Scream 6," and other projects.

The actress had a long-term relationship with Ukrainian boxer Wladimir Klitschko and was his fiancée. In 2014, they had a daughter, Kaya. In 2018, Panettiere gave Klitschko full custody of the child amid treatment for addiction and postpartum depression. Kaya has since lived with her father, who is raising her.

Sources: NBC News, FOX Carolina, People