Selma Blair knew she had a problem before she was diagnosed with multiple sclerosis: She was self-medicating to ease her pain.

But in 2016, she was forced to address the problem after a family vacation ended on a scary note. On a return flight from Cancún, Mexico, to Los Angeles with her son and ex-boyfriend, Jason Bleick, Blair mixed prescription drugs with alcohol. TMZ reported at the time that Blair was crying and saying things like, "He burns my private parts. He won't let me eat or drink," and that she was removed from the aircraft via stretcher and taken to the hospital.

Although she made a public apology following the matter, it's only now that Blair says "the plane incident" was her lowest point with alcohol, adding that she had "too much to drink in Mexico." 

SELMA BLAIR'S MS BATTLE HINDERED HER HOLLYWOOD SUCCESS: 'I COULDN'T EARN MONEY'

Selma Blair in a black blazer with bows stares directly into the camera

Selma Blair got sober following the 2016 plane incident. (Gilbert Flores/Variety via Getty Images)

"I was so messed up and dehydrated and hungover and didn’t know I had neurological issues," Blair told Us Weekly for their new cover story. "I didn’t understand anything. It was horrifying and humiliating. I had to grow up."

Days after the original incident, Blair issued an apology to Vanity Fair.

"I made a big mistake yesterday. After a lovely trip with my son and his Dad, I mixed alcohol with medication, and that caused me to black out and led me to say and do things that I deeply regret," she said in part. "I am a flawed human being who makes mistakes and am filled with shame over this incident. I am truly very sorry."

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Selma Blair in a black dress smiles for a photo

Selma Blair believes her MS wouldn't have been diagnosed if she had still been self-medicating. (Gilbert Flores/WWD via Getty Images)

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It ultimately led the actress to get sober — a decision that she says led her to an MS diagnosis — which she shared publicly in 2018.

"I wouldn’t have been able to be diagnosed with MS unless I was sober. I wouldn’t be a good mom unless I was sober. I self-medicated," she admitted to Us Weekly.

Selma Blair in navy outfit with transparent aviator glasses on stage speaks

Selma Blair says she questioned if she was really sick before getting a diagnosis. (Dimitrios Kambouris/Getty Images for Glamour)

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Before she had an official name for her condition, Blair says she even questioned whether her pain was real.

"I honestly thought I was making it up before I was diagnosed. I just thought, ‘Jesus, Selma, you’re very broken inside. Admit it.’ I didn’t know I wasn’t broken and that I had brain tissue damage," she shared.

According to the Cleveland Clinic, multiple sclerosis can "cause muscle weakness, vision changes, numbness and memory issues." 

Blair has been in remission since 2021.