Christina Applegate is revealing more about her health challenges.

The "Dead to Me" star, 52, opened up about her battle with multiple sclerosis on Monday's episode of Dax Shepard's "Armchair Expert" podcast, telling the host she has "30 lesions" on her brain that she compared to herpes sores.

"So sores all over my brain," she said. "My biggest one is behind my right eye, so my right eye hurts a lot."

The "Anchorman" actress noted that she will sometimes get a "seizurey feeling" in her brain, adding, "I'm not really happy about all the ones in my brain. If you think that I'm just sitting here with 30 lesions on my brain … It's not a fun one to hang with."

According to the Cleveland Clinic, brain lesions are areas of damaged brain tissue that "can disrupt the way your brain works, causing a wide range of symptoms, such as weakness, disruption of one or more senses and confusion." Multiple sclerosis is one of the conditions that can cause brain lesions, the clinic notes.

Christina Applegatemay have had MS symptoms '6 or 7 years' before diagnosis

Applegate was diagnosed with multiple sclerosis while working on the third season of Netflix's "Dead to Me," and she shared news of her diagnosis in 2021. She reflected on "Armchair Expert" that her battle with MS is for "life" and that she isn't sure whether she'll be "around" in 10 years.

"This is the worst thing that's ever happened to me in my entire life," she acknowledged. "I hate it so much, and I'm so mad about it. You can't overcome it."

Although Applegate isn't sugarcoating the difficulty of her MS battle, she expressed regret that she publicly maintained a more sunny attitude while battling breast cancer in 2008. In an interview with Robin Roberts at the time, Applegate, who had undergone a double mastectomy, joked that after reconstructive surgery, she's "gonna have cute boobs till I'm 90."

The actress now says she was "lying my (expletive) off" in this interview about how she felt about the situation.

"I got up and I literally fell into the wall and sobbed because it was a lie," she said. "Everything I was saying was a freaking lie. It was me trying to convince myself of something, and I think that did no service to anyone."

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Earlier this month, Applegate again sat down with Roberts and said she lives "in hell" amid her MS battle. She also revealed she "probably" had MS symptoms for "six or seven years" before being diagnosed.

Applegate recently launched a podcast titled "MeSsy" with Jamie-Lynn Sigler, who also has multiple sclerosis. She has said she expects "Dead to Me" to be her final acting role.

On "Armchair Expert," Applegate and Shepard connected over both being stars who stepped away from acting and started a podcast, although Applegate stressed that she "did not want this" and would be looking for a "cool" project after "Dead to Me" if she were not disabled. But Applegate said she may continue acting via voiceover roles.

"As long as I can speak, I'd love to do that," she said. "That'd be fun. Mama needs to do something."

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Contributing: Naledi Ushe, USA TODAY