The "Two and a Half Men" actor fell ill with pancreas problem after he had a fruit-only diet to prepare for his portrayal as Jobs.
"First of all, the fruitarian diet can lead to like severe issues. I went to the hospital like two days before we started shooting the movie. I was doubled over in pain," aceshowbiz.com quoted Kutcher as saying.
"My pancreas levels were like completely out of whack. It was really terrifying... considering everything," he added.
Jobs died of pancreas cancer in October 2011. He was 56.
Kutcher said he did a lot of research to really get to know Jobs, capturing his hunched walk and demeanour.
"jOBS" releases in the US April 19.