Chronic Fatigue Syndrome vs. Fibromyalgia

Chronic Fatigue Syndrome vs. Fibromyalgia May Not Matter

Senior African American man rubbing his shoulder. Credit: Terry Vine / Getty Images

What's the difference? The issue of chronic fatigue vs. fibromyalgia concerns many people, including doctors, the people who have these disorders, the family and friends who care about them -- and perhaps you as well.

Some doctors treat fibromyalgia (also called fibromyalgia syndrome, or FMS) and chronic fatigue syndrome (CFS, also called myalgic encephalomyelitis, or ME/CFS) separately, while others believe they are actually the same disorder – or, at least, variations of it.

According to the Arthritis Foundation, research shows that 50% to 70% of people with one diagnosis also fit the criteria for the other.

Understanding the Similarities

FMS and ME/CFS are known to have a number of symptoms in common. They include:

Understanding the Differences

One key difference stems from asking the question, "Which of your symptoms is worse, the pain or the fatigue?"

  • Pain is the key symptom in people with FMS.
  • Fatigue is the key symptom in people with ME/CFS.

Fibromyalgia Pain. Usually widespread and chronic, fibromyalgia pain often occurs together with stiffness and so-called “tender points” that hurt when touched and suggest this diagnosis vs. chronic fatigue syndrome.

Fatigue in Chronic Fatigue Syndrome. Far worse than ordinary tiredness, the fatigue of chronic fatigue syndrome can be so severe that the person can’t do anything at all.

Other Significant Differences.

  • Many cases of ME/CFS begin after flu-like symptoms and may be linked to a virus.
  • People with ME/CFS often show chronic immune system activation, as if their bodies are fighting an infection, while people with FMS do not.
  • The diagnostic criteria for ME/CFS include low-grade fever and sore throat, while FMS diagnostic criteria do not.
  • The onset of FMS can often be traced to a physical or emotional trauma.
  • The pain of FMS gets better with heat and gentle massage, while the pain of ME/CFS does not.

The diagnosis could also be influenced by whether your doctor is more familiar with the American College of Rheumatology's criteria for FMS or the guidelines for ME/CFS from the Centers for Disease Control and Prevention (CDC).

Do the Differences Matter?

Actually, some experts say they probably don't. Why? Because treatment for both disorders is focused on relieving symptoms, it tends to be the same or similar for both -- for example, antidepressants, pain medications, and lifestyle changes.

Many people with these disorders also benefit from learning more about them, taking part in local and national support groups (for example, the Arthritis Foundation Self-Help Course), doing low-impact aerobic exercise, and taking low-dose antidepressant medication before bed to improve their sleep.

If you're concerned that you may have FMS or ME/CFS, or if you think your diagnosis of one or the other may need to be reviewed, talk to your doctor. This is especially important if you're being treated for one or the other disorder and not getting the relief you expected.


Klippel J. “Chronic fatigue syndrome and fibromyalgia.” Arthritis Foundation (2016).

“TMJ disorders.” National Institute of Dental and Craniofacial Research (2013).  

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