Selma Blair Opens Up About Her Gripping New Documentary: 'I Want to Tell the Truth About MS'

Although she's been honest and outspoken about the ups and downs of living with MS since going public with her diagnosis in 2018, Selma Blair is offering audiences a powerful, raw look inside what it's really like living with the chronic degenerative neurological disease in her new documentary Introducing, Selma Blair.

"I'm scared because it's a lot," Blair, 49, tells PEOPLE in the latest issue about the film's unfiltered, unflinching perspective, including a particularly challenging time in 2019 when she received a life-altering stem cell treatment to jumpstart her immune system and ease what had been an extended flare-up.

"It was a really hard time in my life," says the Cruel Intentions star. "But I want to tell the truth about MS. It is important to me that people see what living with a chronic illness is like."

Courtesy Discovery+

Shot over 25 days between 2019 and 2020 by filmmaker and now close friend Rachel Fleit, the documentary takes viewers on an intimate journey into the many ups and downs in Blair's life before, during and after her successful treatment.

"Nothing was off-limits," Fleit says of her access. "There was nothing we couldn't show or couldn't talk about. She didn't even do hair and makeup the whole time."

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"Rub it in!" quips the actress. "I was too busy not feeling well. Let's hope that never happens again."

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Fleit says she felt "instantly connected" to Blair when they first met and instinctively knew she wanted to help tell the actress' story.

For much more on Selma Blair, pick up the latest issue of PEOPLE on newsstands Friday

"We have a lot in common, spiritually, emotionally," says the New York-based director. "But then, the first thing she said to me, which has become a little joke that we tell people, is that she has actually alopecia of the eyelash, and she showed me on FaceTime."

(Fleit has alopecia, while Blair has been missing eyelashes due to a side effect from an early medication.)

"I tried to one-up her, okay?" Blair admits. "I can't help it. I'm five years old."

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Fleit says Blair's sense of humor only further helped seal the deal for their future partnership.

"I really enjoyed that about her. And she was immediately sort of disarming and charming, all at once," she says and emphasizes the fact that their film is not a sad story.

"I found this incredible, remarkable subject who was going through something quite intense and extremely painful and difficult that needed to be shown to the world," says Fleit. "There's emotion and pain, but it isn't a sad story. It's actually quite an inspiring one."

Courtesy Discovery+

The film, produced by Mickey Liddell, Pete Shilaimon and Troy Nankin nabbed three Critic's Choice Award nominations including Best Documentary Feature.

It premiered at the 2021 SXSW Film Festival where it won the Special Jury Award for Exceptional Intimacy in Storytelling in the Documentary Feature Competition.

Introducing, Selma Blair is now playing in select theaters and available to stream on discovery+ on Oct. 21.