Playing the King of Rock & Roll did a number on Austin Butler, he says.
The "Elvis" actor, 30, told British GQ that he was hospitalized in March last year and bedridden for a week after completing the film.
"My body just started shutting down the day I finished Elvis," the actor told the outlet, explaining that he "woke up at four in the morning with excruciating pain" and "was rushed to hospital."
According to GQ, Butler said he was diagnosed with a virus that simulates appendicitis. He has since recovered.
The role also took an emotional toll on Butler, who said he related to Elvis Presley's life story on a deep, emotional level. "I've never loved somebody I've never met more than Elvis," he said.
"His mother passed away when he was 23, and my mom passed away when I was 23," Butler told British GQ. "So when I learned that, it was one of those things where I got chills and I just thought, ‘OK, I can connect to that.'"
His portrayal has already been given the stamp of approval from Presley's family. The late singer's ex-wife, Priscilla Presley, took to Instagram on May 6 to sing her praises. "I've seen Elvis the film, I watched the trailer over a dozen times," she wrote alongside the movie's trailer. "But the words I heard from my daughter on how much she loved the film and that Riley will love it too when she sees it brought tears."
Riley Keough, Elvis Presley's granddaughter, has since seen the film. She gave her thoughts during a Variety Women in Motion panel at the Cannes Film Festival, calling the experience of watching it "very emotional."
"I started crying five minutes in and didn't stop," Keough said. "I felt honored they worked so hard to really get his essence, to feel his essence. Austin captured that so beautifully."