Why Is Multiple Sclerosis Misdiagnosis So Common?

The signs and symptoms of multiple sclerosis (MS) overlap with many other conditions. This makes misdiagnosis common.

Further, MS isn't fully understood, which makes differential diagnosis (a way of ruling out or confirming other, similar conditions) a complicated and time-consuming process. Getting an MS diagnosis involves verifying the presence of MS lesions that show up as white spots on MRI (magnetic resonance imaging) scans. Unfortunately, getting an accurate MS diagnosis often takes a long time.

This article discusses the challenges of diagnosing MS and why misdiagnosis can occur.

Doctor examining patient in office

Terry Vine / Getty Images

How Common Is Misdiagnosis?

Approximately 18% of people diagnosed with MS may not actually have the disease. One study found that 50% of misdiagnosed patients carried their MS misdiagnosis for at least three years, and 70% of misdiagnosed patients received disease-modifying therapy (DMT) for a disease they didn't have.

MS Diagnosis

Diagnosing MS is complex. There isn't a singular, definitive test for multiple sclerosis diagnosis. So, getting an MS diagnosis involves a multifaceted diagnostic process that includes:

MS diagnosis typically requires ruling out other conditions that might be causing symptoms through a process called differential diagnosis. For example, there isn't a blood test for MS, but extensive blood work results help rule out or confirm MS mimics, which include many autoimmune and chronic inflammatory diseases with similar symptoms.

In 2017, the McDonald criteria, which is a tool that's considered the gold standard for diagnosing multiple sclerosis using MRI, was updated. This update is expected to reduce misdiagnosis and speed up the diagnostic process, which will give MS patients access to the right treatment options sooner.

According to the McDonald criteria, the key requirement for an MS diagnosis remains evidence of damage to the CNS. More specifically, CNS damage needs to demonstrate dissemination in time (DIT) and dissemination in space (DIS), which means that damage occurred on different dates at least 30 days apart and affected at least two different parts of the CNS. Together, DIT and DIS distinguish MS from other neurological conditions.

Challenges to MS Diagnosis

Because a specific disease biomarker for MS doesn't exist, confirming an MS diagnosis usually isn't a straightforward process. The signs and symptoms of MS manifest in different and unpredictable ways that vary from patient to patient.

A 2016 study found that leading factors contributing to MS misdiagnosis include being thrown off by symptoms caused by other diseases affecting the myelin sheath and misidentifying white spots on the brain in MRIs that look like MS lesions but aren't.

MS isn't the only condition that causes white spots to show up on MRIs, making accurate diagnosis incredibly challenging. For example, migraines can be a cause of non-MS white spots on MRIs.

New Diagnosis Techniques

In March 2022, researchers unveiled a state-of-the-art MRI technique that can identify if the white spots on a patient's MRI are caused by MS or something else by using an imaging biomarker called the central vein sign (CVS) profile. The central vein sign represents a new frontier that shows promise for reducing MS misdiagnosis.

Copycat Conditions

Many diseases and disorders share symptoms with multiple sclerosis. These MS mimics need to be ruled out during differential diagnosis. Some of these conditions include:

Early Signs of MS

Although every individual experiences the early signs of MS uniquely, and no two people are likely to experience the exact same symptoms, there are some common early warning signs of MS, including:

The term "clinically isolated syndrome" (CIS) refers to the first time someone experiences a neurological episode caused by inflammation and damage to their nerves' myelin sheath. CIS is typically followed by a period of recovery when an early warning sign temporarily goes away. MS can only be officially diagnosed after someone has experienced more than one CIS episode.

MS Risk Factors

Identifying risk factors for MS is complicated. Researchers still don't know exactly what causes MS or why some people get it and others don't. That said, growing evidence suggests that exposure to infectious diseases like Epstein-Barr virus may increase your risk of developing MS.

When to See a Healthcare Provider

You should always see a healthcare provider if you're experiencing new MS symptoms. Although acute MS symptoms are distressing and can be painful, they're rarely life-threatening. During MS flare-ups or pseudo-exacerbation, it typically takes over 24 hours to know if you're actually having an MS attack.

You may need to visit the emergency room during an MS attack if you suddenly experience any of the following severe symptoms:

  • Intense pain
  • Vision loss in one or both eyes
  • Suddenly can't walk, use your limbs, or eat
  • High-grade fever (usually 103 degrees Fahrenheit or higher)


MS misdiagnosis is surprisingly common. This is because there is no single test to diagnose MS, and MS can present similarly to other central nervous system conditions. Often, differential diagnosis is needed to rule out other conditions that may be causing symptoms. Updated diagnostic criteria and a new MRI technique that looks at a patient's central vein sign profile show promise for reducing the rate of MS misdiagnosis.

A Word From Verywell

Misdiagnosing MS can have harmful effects. A person may be started on an unnecessary treatment course with possibly detrimental side effects. That's why it's so important to work with your healthcare team to accurately diagnose MS and rule out every other possible reason for your symptoms. Patience is key when getting an accurate MS diagnosis and avoiding misdiagnosis.

Frequently Asked Questions

  • How long does it take to diagnose MS?

    It can take months, or even years, to diagnose multiple sclerosis. There isn't a single definitive test for diagnosing MS. The length of time it takes to diagnose MS depends entirely on individual circumstances and symptoms, which can vary greatly.

  • Why does MS diagnosis take so long?

    MS diagnosis takes a long time because it can't be diagnosed with a single test. Healthcare providers need to rule out other conditions that mimic multiple sclerosis through differential diagnosis, which can take months or even years. Also, an official MS diagnosis requires evidence that damage to the central nervous system occurred in at least two areas and happened 30 days apart.

  • What are the early symptoms of MS?

    The most common early symptoms of MS include blurry or foggy vision, numbness and tingling sensations, or weakness and fatigue. Other early warning signs of MS include inflammation of the optic nerves and muscle spasms. Everyone experiences MS differently. Early symptoms will always vary.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Christopher Bergland
Christopher Bergland is a retired ultra-endurance athlete turned medical writer and science reporter.