The Oscar-nominated actress is unrecognisable in the film, in which she plays televangelist Tammy Faye Bakker, with her alabaster complexion transformed into a deeply tanned visage.
And in an interview with the Los Angeles Times, Jessica admitted her skin will be paying for the transformation for years to come.
"I think for sure I've done some permanent damage to my skin on this," she sighed. "Listen, I eat very pure and I take very good care of my skin and I stay out of the sun and all that stuff. But it's heavy. And when you're wearing it all day every day - the weight of it on your body, it stretches your skin out. I finally took it off and I was like, 'I look 50 years old!' No, I'm kidding. But it's fine. It's for my art."
While it normally took around four hours per day to do her make-up, Jessica was actually sitting in the chair for nearly eight hours one day - which took its toll.
"It was like going on a long-distance flight every day," she admitted. "Because if it takes seven-and-a-half hours to put on, it's going to take at least two hours to get off. It was concerning to me. I was worried about my circulation. By the time I got on set that first day that was seven-and-a-half hours, I was like, 'I have no energy left.' And she's supposed to show up with so much energy."
"That was the '90s look - the very end. That's the most prosthetics I've worn. Even the bronzer and the foundation are so much darker, the lashes are thicker. The make-up gets heavier as she gets older."
"The Eyes of Tammy Faye" is released in cinemas on 17 September (21).