Comparison of Fibromyalgia and MS

Multiple sclerosis (MS) and fibromyalgia share many symptoms. For instance, depression is a common symptom in both conditions and may be a result of the disease process itself, a consequence of having such a debilitating disease, or a little bit of both. 

Other commonly shared symptoms include:

• Fatigue
• Pain
• Sleep disturbances
• Cognitive problems
• Headaches and migraines
• Bladder and bowel problems
• Negative impact on quality of life and ability to perform everyday activities 

This overlap in symptoms may confuse a diagnosis of fibromyalgia and multiple sclerosis, especially with someone already living with one of these conditions. In other words, it's plausible that doctors, and people living with the disease themselves, would naturally assume that the symptoms were part of the original diagnosis and be hesitant to investigate further.

Incidence of Fibromyalgia and Multiple Sclerosis

Fibromyalgia is much more common than multiple sclerosis, as it's estimated that six to ten percent of people in the U.S. have fibromyalgia. In contrast, MS affects less than 10 percent of that number or a roughly estimated 400,000 people in the US.

That said, one link shared between fibromyalgia and relapsing-remitting MS (the most common type of MS) is that both diseases are more common in women, although men and children can develop them too.

Diagnosis of Fibromyalgia and Multiple Sclerosis

While there are no blood tests to definitively diagnose fibromyalgia or multiple sclerosis, there are specific criteria used by a doctor to confirm that a person does indeed have the condition. These criteria greatly help to prevent a misdiagnosis, which can be devastating for a person. Still, the diagnostic process can be challenging for some people, as clinical symptoms can overlap.

Fibromyalgia is diagnosed when a person meets one of the two criteria:

• A Widespread Pain Index Score that is 7 or greater and Symptom Severity Scale Score that is 5 or greater OR
• A Widespread Pain Index Score that is 3 to 6 and a Symptom Severity Scale Score that is 9 or greater.

Widespread pain index (WPI) ranges in score from 0 to 19 and is based on the number of sites that a person reports pain over the past week. For example, pain in the right lower leg, left lower leg, abdomen, left hip, and left jaw would be a score of 5.

The Symptom Severity (SS) scale score is the sum of severity scores (ranging from 0 to 3) of the following four symptoms: fatigue, waking unrefreshed, cognitive symptoms, and extent of general somatic ("body") symptoms for a total score of 0 to 12.

Diagnosis of multiple sclerosis relies heavily on the presence of lesions on the brain or spinal cord, as seen on an MRI scan. MS can also be diagnosed clinically, meaning a person has symptoms that occur at different periods of time (at least one month apart) and within different parts of the brain, spinal cord, or optic nerve (at least 2 different areas).

One of these episodes (called a relapse) must be confirmed by either a neurological examination, and MRI, or a test called visual evoked potentials (if there are vision problems). 

When confirming a diagnosis of MS, a neurologist will also want to rule out other diseases that can mimic MS besides fibromyalgia. This may mean performing blood tests and/or a lumbar puncture. 

A Word From Verywell

Given the overlap in many of the symptoms of these diseases, as well as the similar risk profiles and diagnostic challenges, it's possible there are people who have both MS and fibromyalgia, or that one is mistaken for the other.

If you are concerned about this, it's sensible to ask for a referral to a rheumatologist (or a neurologist for MS symptoms) to get additional information and a second opinion.

That said, it's important to understand that having one condition does not put you at risk for having the other—meaning if you have been diagnosed with fibromyalgia, it does not mean you have a higher chance of developing MS (and vice versa).

There is no cure for either disease, but there are medications to treat many of the symptoms. For MS, disease-modifying medications can keep your MS from progressing too.

The bottom line here is that it's worth your time and effort to keep asking questions and remain proactive in seeking out improved health and a better quality of life.