Authorities announced on Tuesday that Hayden Panettiere died of an overdose involving fentanyl combined with several other drugs.

The finding names the synthetic opioid fentanyl as a central factor in the actor's death. According to the authorities, toxicology also detected three additional substances in her system: alprazolam, methocarbamol and quetiapine.

Each of those drugs carries a distinct pharmacological profile. Alprazolam, sold widely under the brand name Xanax, is a benzodiazepine prescribed for anxiety. Methocarbamol is a muscle relaxant. Quetiapine, known by the brand name Seroquel, is an antipsychotic medication used to treat conditions including bipolar disorder and schizophrenia. The combination of an opioid with a benzodiazepine in particular is a pattern that has long alarmed public health officials, because both classes of drugs suppress respiratory function.

The announcement came weeks after Panettiere was featured in an Emmys tribute this month. Her inclusion in the televised memorial segment had already drawn attention to her passing among viewers and colleagues in the entertainment industry.

The confirmation by the authorities on Tuesday answers the central question surrounding the circumstances of her death, replacing speculation with an official determination. Fentanyl, a synthetic opioid many times more potent than heroin, has driven a surge in overdose deaths across the United States in recent years, and its presence in high-profile cases has repeatedly intensified public discussion of the crisis.

Panettiere built her career across television and film, and her death prompted an outpouring of tributes from fans and fellow performers. The Emmys tribute this month placed her among the artists and industry figures honored by the television academy.

No further details beyond the substances identified were included in the authorities' statement. The official determination now stands as the authoritative account of the cause of death, and it is likely to shape how her passing is discussed both within the industry and in the broader conversation about opioids and polysubstance use.