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Coroner: Stephan Bonnar, UFC Hall of Famer, died of accidental fentanyl overdose

The 9th Annual Fighters Only World Mixed Martial Arts Awards at The Venetian Theatre Inside The Venetian Las Vegas Photo by David Becker/WireImage

Stephan Bonnar died of an accidental drug overdose.

The Clark County (Nev.) coroner’s office ruled Bonnar’s death accidental from “Fentanyl, Parafluorofentanyl and Mitragynine intoxication” in an email sent to MMA Fighting after a public records request following the UFC Hall of Famer’s death on Dec. 22 in Las Vegas. He was 45.

The coroner’s office declined to provide additional details on Bonnar’s death, citing medical privacy laws. Typically, the office determines a cause and manner of death within 90 days, but a spokesperson said Bonnar’s case took additional time due to additional testing performed during an autopsy.

Fentanyl is a synthetic opioid at the center of the ongoing opioid crisis. It is 100 times more potent than morphine and has been linked to thousands upon thousands of overdose deaths in the U.S., many due to unintentional ingestion. Bellator fighter Jordan Young’s death was ruled an accidental overdose due to Fentanyl and alprazolam (Xanax) intoxication.

Parafluorofentanyl is an analogue of fentanyl, while Mitragynine is an active compound of the legal painkiller Kratom.

The UFC first confirmed Bonnar’s death and said that while the official cause of Bonnar’s death was pending, he was believed to have died due to “presumed heart complications.”

Bonnar openly discussed his use of opioids during a September 2021 interview with MMA Fighting, revealing a 30 mg/day regimen of oxycodone he used legally to treat long-term injuries from fighting and pro wrestling. He lashed out at the question of whether he abused the drugs after a video he filmed of a hospital confrontation went viral. He later revealed he had almost died from a severe staph infection and said he was lucky to be alive.

Bonnar said he had been “blacklisted” from the UFC following a positive drug test stemming from his 2012 fight with Anderson Silva. After his death, the promotion held a tribute to The Ultimate Fighter 1 finalist and Hall of Famer. Leading it was Forrest Griffin, the opponent Bonnar battled in a fight widely credited for saving the UFC.

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