Christina Applegate 'back at square one' after MS misdiagnosis confirmed

Christina Applegate has delivered a stunning revelation, disclosing that the multiple sclerosis diagnosis she has lived with since 2021 was wrong, and that she now faces the daunting prospect of starting her medical journey from scratch. The 54-year-old actor made the disclosure on her podcast this week, saying her doctor delivered the unexpected news with the words: "Congratulations, you don't have MS."

Far from being a relief, Applegate described the moment as deeply unsettling. She is still using a wheelchair and walking aid, her symptoms have in some ways worsened, and she has no explanation for what has been causing her debilitating illness.

How the misdiagnosis unfolded

Applegate was first told she had multiple sclerosis in 2021, during the production of the third and final season of her Netflix drama. The diagnosis came after she developed a wide range of severe symptoms consistent with the disease, including muscle and motor difficulties, fatigue and other neurological issues that forced significant changes to her daily life.

Over the years that followed, she became a prominent voice for people living with MS, attending major public events including her Hollywood Walk of Fame induction in 2022 and the Primetime Emmys in 2024, where she presented an award while relying on a cane and wheelchair.

Her doctor had her undertaking a course of infusions over an extended period, a treatment with significant physical demands. When those infusions were eventually stopped to observe how her immune system responded, the results were unexpected. In a typical MS patient, removing such treatment causes levels of B cells to fluctuate noticeably. In Applegate's case, her B cell levels stayed stable, raising serious doubts about the original diagnosis.

"I had every symptom of someone with MS. Every single one," she said on the MeSsy podcast, which she co-hosts with actor Jamie-Lynn Sigler. "You're not going to freaking believe this."

Applegate's reaction: 'Nothing magical happened'

While those close to her reportedly cried with happiness at the news, Applegate said she felt no such joy. She emphasised that a corrected diagnosis does not mean a corrected health situation.

"You don't get misdiagnosed, and all of a sudden 'I'm better'," she said. "I haven't gotten better, Jamie. If anything, I've gotten worse in some ways."

She told her co-host she still cannot walk unaided from a car to a medical appointment and continues to rely on a wheelchair when visiting doctors. The announcement that she does not have MS has not unlocked any new clarity about her condition.

"Nothing magical happened when she said, 'You don't have MS'. Nothing magical happened. So, I'm back at square one, that I don't know what's going on with me," she said.

Applegate also spoke about the emotional weight of having become a public face of the MS community, only to learn the diagnosis was incorrect. "I feel like I let everybody down," she said, adding that she previously had at least a framework for understanding why each day was so difficult. "I had a reason as to why my day sucked every day and now I don't have a reason. It's very unnerving and it's really confusing for me."

She confirmed she is now undergoing further testing to identify what is actually causing her symptoms, though no answers have emerged yet.

Why MS misdiagnosis is more common than many realise

Applegate's experience is not isolated. Multiple sclerosis is a chronic condition in which the immune system attacks the central nervous system, affecting motor function, vision, cognition, sensation and causing pain and fatigue. It affects more than 37,000 Australians and an estimated three million people worldwide, with women diagnosed at roughly three times the rate of men.

One of the central challenges with the disease is that there is no single definitive test for it. Neurologists must piece together a picture using patient history, neurological examination, MRI findings and, where applicable, analysis of cerebrospinal fluid. MRI scans can show abnormalities that closely resemble MS but are in fact attributable to other causes entirely, including migraines, ageing or small-vessel disease.

A study published in 2019 found that 18 per cent of new MS patients admitted to two United States clinics had been misdiagnosed. Professor Todd Hardy, a neurologist at the University of Sydney, has noted that symptoms can be highly variable and frequently overlap with other conditions, making confident diagnosis genuinely difficult even for specialists.

One Sydney woman, who asked to be identified only by a pseudonym for privacy reasons, spent nine years believing she had MS before a new neurologist and an ear, nose and throat specialist determined her primary symptom of dizziness was caused by untreated crystals in her ear, a condition producing severe vertigo. Once that was treated, her dizziness resolved and she was cleared of the MS diagnosis.

Her reaction differed from Applegate's. While she acknowledged the years of unnecessary treatment and isolation were painful, she described feeling relief rather than anger at the corrected outcome.

Cases such as these raise difficult questions about diagnostic pathways for complex neurological conditions. The misdiagnosis issue is not unique to MS: a misdiagnosis can carry severe consequences, as documented in other cases where patients underwent major medical treatment based on an incorrect assessment.

For Applegate, the road ahead remains deeply uncertain. After years of living with a named condition and its corresponding treatment plan, she is now navigating a medical situation without a diagnosis, without a clear cause and, for the moment, without answers.