Demi Moore's latest role is a horror film, but it turns out the actress was battling some horrific conditions off-screen too.

In a recent interview with the Los Angeles Times, the actress — who is currently promoting "The Substance" — revealed how the role impacted her physically.  

"To give you an idea of the intensity, my first week that I actually had off, where it was just Margaret (Qualley) working, I got shingles," Moore told the outlet. "And I then lost, like, 20 pounds."

In the film, Moore plays a 50-year-old celebrity who finds a way to temporarily make herself younger with an experimental drug.

DEMI MOORE, 61, FELT LIKE THERE WASN’T A PLACE FOR HER IN HOLLYWOOD AFTER 40

Demi Moore smiles on red carpet.

Demi Moore revealed she battled shingles and lost 20 pounds while filming her latest role. (Getty Images)

"Oh, yeah, I had crazy acne for a full, long-ass time," Qualley, who portrays Moore's clone in the film, added. 

"You have to walk away feeling that you put it all on the table," Moore added. "It called for it and it’s what you want to bring to it."

According to the Mayo Clinic, shingles is a viral infection that causes a painful rash. It can occur anywhere on your body, but typically looks like a single stripe of blisters that wraps around the left side or the right side of your torso. Shingles is caused by the varicella-zoster virus (VZV) — the same virus that causes chickenpox. 

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Demi Moore speaking

The 61-year-old actress plays a 50-year-old celebrity who finds a way to temporarily make herself younger with an experimental drug in her new film, "The Substance." (Jared Siskin/Patrick McMullan via Getty Images)

During a recent chat with Interview magazine, the mom of three opened up about her career in Hollywood and why she felt like she didn't belong at one point. 

"I had done ‘Charlie’s Angels,’ and there was a lot of conversation around this scene in a bikini, and it was all very heightened, a lot of talk about how I looked," Moore told the outlet. 

"And then I found that there didn’t seem to be a place for me. I didn’t feel like I didn’t belong. It’s more like I felt that feeling of, ‘I’m not 20, I’m not 30,’ but I wasn’t yet what they perceived as a mother."

Moore also called her new movie a "unique way to be exploring this issue of aging, of societal conditioning, of what I also see as the pressure of the male-idealized woman that we as women have bought into."

Demi Moore

Moore has been open about age discrimination in Hollywood.  (Photo by Kevin Mazur/MG19/Getty Images for The Met Museum/Vogue)

"At the core of it, what it’s really about is what we do to ourselves, and I loved that it was illustrated in such a physical way, showing that violence with what we do with our thoughts, how we attack ourselves and distort things," she said. "There’s great power in knowing that what we do to ourselves is a choice, and we can make a different choice." 

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Moore, who has been dubbed a "sex symbol" throughout her career, further explored this topic during a chat with Kelly Ripa. 

"I realize I really like being busy. And you said something earlier, ‘Oh, my career’s always been on fire.' And I will tell you that’s actually not true. When I hit 40, I feel like they didn’t know what to do with me," she told the daytime talk show host during an episode of the "Let’s Talk Off Camera" podcast. "Now I feel like women in their 40s — it’s a shift in perception — but I was part of the transitioning crowd, and they were a bit like, ‘We don’t have anything for you.’" 

Demi Moore ain a white polka dot dress at Cannes

Moore has three children with ex-husband, Bruce Willis.  (Kristy Sparow/Getty Images)

Moore said she was told at the time she looked "too young" to play certain parts, but she wasn't 30, which made her too old for many parts. 

"And I literally, I was told, ‘We don’t really know what to do with you.' What’s been interesting, seeing the shift we’ve gone through," Moore said. 

She added that streaming services have started to realize "there is a huge demographic that wants to be served. That’s powerful women and, in some cases, women not 30, women not 40, women in their 50s, 60s, 70s, and it’s exciting." 

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Fox News Digital's Brie Stimson contributed to this post.