Actor Christina Applegate, who shared in 2021 that she had been diagnosed with multiple sclerosis (MS), said on her podcast MeSsy that her doctor has now told her she does not have MS. She said she still has MS-like symptoms and does not yet have a new diagnosis, telling listeners she is “back at square one where I don’t know what’s going on with me,” according to the Associated Press and ABC News.
Her news has many people with MS asking a hard question: could my diagnosis be wrong too? This guide explains how MS is diagnosed, how often misdiagnosis happens, which conditions can mimic MS, and what to do if you are worried.
QuickRx does not know and does not speculate about any individual’s medical condition. Details about Ms. Applegate come only from her public statements as reported by the news sources linked above.
Can MS Be Misdiagnosed?
Yes, MS can be misdiagnosed, because there is no single test that proves a person has it.
Doctors diagnose MS by putting together your symptoms, a neurological exam, MRI scans of the brain and spinal cord, and sometimes a spinal tap (lumbar puncture) to look for signs of inflammation in the spinal fluid, while ruling out other conditions that can look similar (NHS; MedlinePlus). To confirm MS, neurologists use a set of rules called the McDonald criteria, which require evidence of damage in more than one area of the nervous system and at more than one point in time. When those rules are stretched, or when MRI spots from another cause are read as MS, a wrong diagnosis can happen.
General information only. How MS is diagnosed can vary by patient and by doctor; your neurologist can explain how your own diagnosis was made.
How Common Is MS Misdiagnosis?
In one 2019 study, about 1 in 5 patients referred to two MS specialty centers with an MS diagnosis turned out not to have MS.
The same study found that many of those patients had taken MS medicines they did not need, some with serious possible side effects. That is why getting the diagnosis right matters so much, in both directions.
What Conditions Can Mimic MS?
Several conditions can cause MS-like symptoms or MS-like spots on an MRI, including migraine, NMOSD, MOGAD, lupus, vitamin B12 deficiency and functional neurological disorder.
Migraine
The most common correct diagnosis among misdiagnosed patients in the 2019 study, at 16% (Multiple Sclerosis and Related Disorders, 2019).
NMOSD (neuromyelitis optica spectrum disorder)
An autoimmune disease that attacks the optic nerves and spinal cord and can look a lot like MS. A specific blood test for antibodies helps tell them apart (NINDS).
MOGAD (MOG antibody-associated disease)
Another antibody-driven condition that can cause optic neuritis and spinal cord inflammation, and that has been mistaken for MS. It is also confirmed with a blood test (National MS Society; case report).
Lupus
Lupus is an autoimmune disease that can affect many organs, including the brain, spinal cord and nerves (MedlinePlus; Lupus Research Alliance).
Vitamin B12 deficiency
Low B12 can cause nerve problems such as numbness and tingling in the hands and feet, balance trouble and memory problems (NIH Office of Dietary Supplements).
Functional neurological disorder (FND)
Real, often disabling symptoms such as weakness or trouble walking that come from a problem with how the nervous system works, without nerve damage that tests can find (MedlinePlus).
This list is general information and is not complete. It is not a list of what any specific person has. Only a doctor who examines you and reviews your tests can diagnose you.
MS vs Lupus: How Are They Different?
MS mainly targets the brain, spinal cord and optic nerves, while lupus is a body-wide autoimmune disease that can also affect the skin, joints, kidneys and blood (MedlinePlus; MedlinePlus).
Because lupus can also involve the nervous system (Lupus Research Alliance), the two can overlap in symptoms like fatigue, numbness and thinking problems. Blood tests, the pattern of symptoms outside the nervous system, and MRI findings help doctors tell them apart.
General information only; it does not replace an evaluation by a rheumatologist or neurologist.
What Should You Do If You Think Your MS Diagnosis Is Wrong?
The safest first step is to keep taking your medicine and talk to your neurologist about how your diagnosis was made.
Bring a list of questions to your next visit: what findings led to the diagnosis, whether antibody blood tests for NMOSD or MOGAD were done, and whether your MRI is typical for MS. If you still have doubts, ask for a referral to an MS specialty center for a second opinion.
“News like this is scary if you live with MS. If it has you questioning your own diagnosis, please don’t stop your medicine on your own. Write down your questions and bring them to your neurologist. And if your treatment plan changes, our navigators are here to help you sort out coverage and costs for whatever comes next.
Julia Kravtsova, PharmD
Head Patient Navigator, QuickRx Specialty Pharmacy
Worried About Your Own MS Diagnosis? Read This First
- Do not stop or change your MS medicine on your own. Always talk to your neurologist first.
- Ask your neurologist what your diagnosis was based on: your symptoms, your MRI, and any spinal fluid or blood tests.
- If something does not add up, it is reasonable to ask for a second opinion at an MS specialty center.
- Call 911 or go to the emergency room for sudden vision loss, sudden weakness, trouble speaking or trouble breathing.
How QuickRx Supports People Living With MS
QuickRx is a specialty pharmacy that fills MS medicines and helps patients sort out coverage, prior authorizations and the cost of treatment.
Our patient navigators check copay programs, patient assistance programs and foundation grants you may qualify for and apply on your behalf, free of charge. Eligible patients may pay $0. Learn more about our specialty medication copay assistance or call (917) 830-2525.
Copay cards, patient assistance programs and foundation grants are offered and controlled by their sponsors, not by QuickRx. Eligibility is set by each sponsor, not every patient qualifies, and programs may change or close at any time.
Frequently Asked Questions
Can MS be misdiagnosed?
Yes. There is no single test for MS, so doctors combine symptoms, an exam, MRI scans and sometimes spinal fluid tests, and rule out other conditions. In one 2019 study, about 1 in 5 patients referred to two MS centers with an MS diagnosis did not have MS (Multiple Sclerosis and Related Disorders, 2019).
What did Christina Applegate say about her MS diagnosis?
On her podcast MeSsy, she said her doctor told her she does not have MS, that she still has MS-like symptoms, and that she does not yet know what is causing them, according to the Associated Press.
What conditions are most often mistaken for MS?
In the 2019 study, the most common correct diagnosis was migraine (16%). Other conditions that can mimic MS include NMOSD, MOGAD, lupus, vitamin B12 deficiency and functional neurological disorder.
How is MS diagnosed?
Neurologists use the McDonald criteria, which look for evidence of damage in more than one area of the nervous system at more than one point in time, using your symptoms, exam, MRI and sometimes a spinal tap (McDonald criteria; NHS).
Should I stop my MS medicine if I think I was misdiagnosed?
No. Do not stop or change any MS medicine without talking to your neurologist first. Ask your neurologist how your diagnosis was made, and consider a second opinion at an MS specialty center.
Can a blood test rule out MS?
No blood test can confirm MS, but blood tests can find conditions that look like MS, such as NMOSD and MOGAD antibodies, vitamin B12 deficiency or lupus (NINDS; NIH Office of Dietary Supplements).
Sources and Further Reading
- Associated Press: Christina Applegate says her doctor told her she was misdiagnosed with MS (Oct 20, 2026)
- ABC News: Christina Applegate says she was misdiagnosed with MS (Oct 20, 2026)
- Kaisey M, et al. Incidence of multiple sclerosis misdiagnosis in referrals to two academic centers. Mult Scler Relat Disord. 2019;30:51-56
- Thompson AJ, et al. Diagnosis of multiple sclerosis: 2017 revisions of the McDonald criteria. Lancet Neurol
- NHS: Multiple sclerosis diagnosis
- MedlinePlus: Multiple Sclerosis
- NINDS: Neuromyelitis Optica Spectrum Disorder
- National MS Society: MOGAD
- MedlinePlus: Lupus
- NIH Office of Dietary Supplements: Vitamin B12
- MedlinePlus: Functional neurologic disorder
Medical Disclaimer: This article is for general information only and does not replace advice from your doctor. It does not diagnose any condition, and QuickRx does not speculate about any individual’s health. Do not start, stop or change any medication without talking to your prescriber. If you have new or worsening symptoms, contact your healthcare provider; for an emergency, call 911.
Written by: Paola Larrabure, Pharma Content Manager
Clinically reviewed by: Julia Kravtsova, PharmD, Head Patient Navigator
Last updated: October 20, 2026
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