Kasey Kahne will miss at least three more races while trying to determine what is causing severe dehydration issues when he competes in NASCAR Cup Series events.
Regan Smith, who substituted for Kahne and finished 20th on Monday in the Brickyard 400 at Indianapolis Motor Speedway, will replace Kahne in the Leavine Family Racing car at Las Vegas Motor Speedway this weekend as well as the following weeks at Richmond Raceway and the Charlotte Motor Speedway road course.
Kahne fought nausea and had trouble seeing for the final 100 laps Sept. 2 at Darlington Raceway, as he was unable to replace the fluids he was sweating out throughout the race. He had similar, but not as severe, issues last year at Indianapolis and this year at Kentucky and Bristol.
"I definitely shouldn't have been in the race car anymore," Kahne said last week about the end of the Darlington race. "I stayed out there, put my body through it, my brain, my head. It was really difficult.
"I think it's just better off for me to stay home and figure out how to help the situation before I get back in the car."
Kahne, who is 28th in the NASCAR Cup Series standings, is retiring from full-time Cup racing after this season. He tweeted Wednesday that he won't accelerate his retirement because he's not ready to give up racing.
Kahne also said last week that he has no issues in practice and that he hydrates himself well during the week. He indicated that doctors told him he could do damage to his body if he continues to race without knowing whether he will get dehydrated.
"I'm fine for 50 minutes, an hour and a half, two hours," he said. "Once you get past that point in time, you can't catch up. You've been losing throughout all that.
"Then I quit drinking as much always because I start trying to throw up. You're not putting anything in, and you're losing even more. It just gets so far behind that, you know, your heart is trying to help cool you off, hydrate you, but there's nothing else to use."