What's the Difference between Fibromyalgia and Chronic Fatigue Syndrome?

By Kristi Patrice Carter

Figuring out the differences between Fibromyalgia and Chronic Fatigue Syndrome is one of the major medical challenges of the last ten years. A major question that still dominates the medical establishment is whether they are related, unrelated, or identical; they just originate with the pushing of different “buttons”.

Some experts think that they are definitely two distinct diseases. Others feel that they are separate, but with common symptoms. Still others believe that they are different iterations of the same illness.

As if that were not enough, many people who have Chronic Fatigue Syndrome also have Fibromyalgia, and vice versa. Some experts have said they believe that up to 70% of all Fibromyalgia sufferers also have symptoms that fit the criteria for Chronic Fatigue Syndrome. The overlap creates a very difficult process of figuring out the disease, cause, unique symptoms, and treatment. 

Part of the confusion is that it is emerging and becoming accepted in the medical community that both illnesses are part of a new medical category called Central Sensitivity Syndromes. This newly emerging group include other illnesses such as migraines, irritable bowel syndrome, TMJ, multiple chemical sensitivities, restless legs syndrome, myofascial pain syndrome, and, of course, Fibromyalgia and Chronic Fatigue Syndrome. The central focal point of these illnesses is that whatever their cause, they seem to all have a sensitization of the central nervous system. 

There are, however, some differences, although not many that have been identified. The most significant between the two is that with Fibromyalgia, pain is a predominant symptom. With Chronic Fatigue Syndrome, fatigue is the most dominant symptom. There are other differences but in terms of symptoms, far more are shared by both than differ.

Other key differences include the levels of Substance P, a neurotransmitter that transmits pain signals. These are usually elevated in Fibromyalgia but not in Chronic Fatigue Syndrome. Additionally, Fibromyalgia sufferers almost always have higher levels of Substance P.

Chronic Fatigue Syndrome sufferers also usually have elevated levels of RNasel. RNasel is a cellular antiviral enzyme that fights illness. Patients with Fibromyalgia almost never have elevated levels of RNasel. This is important as it also is a suspected cause in another key difference between the two.

Chronic Fatigue Syndrome sufferers will often have symptoms or bouts kicked off by flu-like or other infectious illnesses. Patients with Fibromyalgia will more often have their episodes initiated by some trauma to the body. These could include accident, illness, surgery, or high stress instances. 

As a result of the similarities of the illnesses, the doctor you see and their beliefs or experience will often dictate which disease you are diagnosed with. If you consult an infectious disease specialist, they are likely to diagnose Chronic Fatigue Syndrome. If you consult a rheumatologist, they are likely to diagnose Fibromyalgia. 

The trick is to figure out your doctor’s specialization and then identify the nature of your symptoms. If you get sick after a cold or flu and have long bouts of fatigue, the chances are greater that you have chronic fatigue. If you get sick after some sort of trauma, even mild traumas such as cutting your finger on a knife, and then experience the pain symptoms of Fibromyalgia, you probably have that. 

Taking one diagnosis verbatim is probably not a good idea. Although the treatments are very similar, your diagnosis might be impacted by research development as these diseases gain more prominence. Getting a second opinion is recommended.