'The Substance' star Demi Moore battled shingles, lost 20 pounds while filming horror movie

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...