What happened to Kyle Busch? Florida doctor explains NASCAR star's sudden cause of death, signs to look for

Florida doctor explains Kyle Busch's cause of death: Sepsis

Two-time NASCAR Cup Series Kyle Busch died from severe pneumonia that progressed into sepsis, a family statement said. He was 41 years old. Dr. Jamin Brahmbhatt, a doctor at Orlando Health, explained that sepsis is unpredictable. 

The passing of two-time NASCAR Cup Series Champion Kyle Busch was sudden to all. On Thursday evening, May 21, NASCAR confirmed that the 41-year-old racing icon had died, just hours after his family announced he would sit out the upcoming Coca-Cola 600 at Charlotte Motor Speedway.

Family statement ‘Pneumonia progressed to sepsis’

According to a family statement, obtained by FOX Sports reporter Bob Pockrass, Busch died from pneumonia that progressed into sepsis. 

"The medical evaluation provided to the Busch Family concluded that severe pneumonia progressed into sepsis, resulting in rapid and overwhelming associated complications," the family statement said. 

Busch, who was preparing to race Sunday at the Coca-Cola 600 at Charlotte Motor Speedway, experienced shortness of breath, felt he was overheating and was coughing up blood, according to a 911 call obtained by the AP.

Dr. Jamin Brahmbhatt, a urologist and surgeon at Orlando Health, spoke with FOX 35's Hannah Mackenzie about how "unpredictable" sepsis can be. 

DAYTONA BEACH, FLORIDA - FEBRUARY 11: Kyle Busch, driver of the #8 zone Jalapeno Lime Chevrolet, looks on during qualifying for the NASCAR Cup Series Daytona 500 at Daytona International Speedway on February 11, 2026 in Daytona Beach, Florida. (Photo

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How does pneumonia turn into sepsis? 

"Not every cough is going to lead to pneumonia, not every pneumonia is going to lead to sepsis," Brahmbhatt said. 

Sepsis is the "huge inflammatory response" that happens when the body is trying to fight the infection, Brahmbhatt explained. 

Sepsis is unpredictable, Brahmbhatt said, saying sepsis isn't triggered by age or what infection you have. Symptoms of sepsis typically include fast, shallow breathing, feeling light-headed or shivering. If it progresses into your organs, your organs can start failing, Brahmbhatt said. 

Florida doctor explains Kyle Busch's cause of death: Sepsis

Two-time NASCAR Cup Series Kyle Busch died from severe pneumonia that progressed into sepsis, a family statement said. He was 41 years old. Dr. Jamin Brahmbhatt, a doctor at Orlando Health, explained that sepsis is unpredictable. 

‘Catch sepsis early’

It's unpredictable how quickly sepsis happens, Brahmbhatt said, recommending people catch signs and symptoms of sepsis early and seek medical attention. 

"When it comes to sepsis, time matters," he said. "The quicker you get evaluated, the quicker you get treatments, the better prognosis you have." 

What we don't know:

It's not known how long Busch's body was trying to fight the lung infection. 

Fox News senior medical analyst Dr. Marc Siegel told Fox News Digital that Busch had an upper respiratory sinus infection which progressed to pneumonia. 

In a statement before his death, Busch's family said he was hospitalized for a severe illness and was currently undergoing treatment. 

Tributes pour out for Kyle Busch

Busch was beloved in the racing world. Having joined the Cup Series in 2004 and winning the championship twice – in 2015 and 2019 – Busch leaves behind a legacy that is felt deeply by competitors, fans, and friends alike.

American racer Ryan Blaney shared a memory from 2017 where he ran into Busch in a hotel lobby in Las Vegas and went out together. The next day, Blaney recalled asking where Busch was and only seeing his feet stick out from underneath a table cloth from the table Busch was under. Busch was wearing his yellow M&Ms suit. 

"He was all-around a good person," Blaney said. "I had a lot of good times getting to know him and competing against him."

Tyler Reddick remembered Busch as someone who was always raising the bar. 

"Kyle, every aspect of racing, was on top of it," Reddick said.