What’s the Difference Between Chronic Fatigue Syndrome and Fibromyalgia?

Chronic fatigue syndrome and fibromyalgia are similar conditions with some key differences. They’re both considered central sensitivity syndromes, with both involving fatigue, pain, and cognitive dysfunction.

Chronic fatigue syndrome (also called myalgic encephalomyelitis or ME/CFS) is more often tied to immune-system abnormalities than fibromyalgia. And fibromyalgia is generally more painful than ME/CFS.

But both conditions affect multiple systems in the body. They’re sometimes referred to as neuroimmune or neuroendocrineimmune disorders to reflect that.

This article will explore the causes and symptoms of these conditions, whether you can have both, and how they’re diagnosed and treated.

Chronic Fatigue Syndrome vs. Fibromyalgia Causes

The causes of ME/CFS and fibromyalgia aren’t well understood. They’re both believed to result from a combination of factors rather than a single cause. 

ME/CFS Causes

Research suggests ME/CFS can be caused by:

• Infections: Epstein-Barr virus (a member of the herpes virus family that causes mononucleosis), Ross River virus (passed by mosquitos), Coxiella burnetti bacteria (cause Q fever, a disease passed from animals to humans), and some other pathogens may lead to ME/CFS in some people.
• Immune system changes: Autoimmunity or autoimmune-like qualities, chronic activation, overproduction of some cells and an abnormal function of others can occur.
• Stress system changes: A dysregulated stress-response system affects the immune system, increasing inflammation.
• Energy production changes: The cells don’t produce energy properly, leaving the body depleted.
• Genetics: ME/CFS tends to run in families. The exact genes involved aren’t yet identified.

Each person has their own mix of factors. The illness may start after a flu-like illness (infection) or stressors such as a car accident, surgery, or other traumatic events.

Fibromyalgia Causes

Suspected causes of fibromyalgia include:

• Hormonal changes: Pregnancy, menopause, and hysterectomy—fibromyalgia is much more common in women/people with a uterus and ovaries.
• Stressful events: Events include premature birth, childhood abuse, and car accidents.
• Infections: Some cases start after viral illnesses.
• Chronic pain: Chronic pain changes how the brain processes pain signals, a key component of fibromyalgia.
• Chronic sleep deprivation: Sleep disorders are common before fibromyalgia develops.
• Mood disorders: Conditions like anxiety, depression, and post-traumatic stress disorder (PTSD) involve similar brain-chemistry changes and often precede fibromyalgia.
• Genetics: Fibromyalgia tends to run in families; the exact genes haven’t yet been identified

Fibromyalgia has some qualities in common with autoimmune diseases. Some cases of fibromyalgia may be autoimmune, but more research is needed.

CAUSAL FACTORS	ME/CFS	FIBROMYALGIA
Infections	Yes	Yes
Immune system changes	Yes	Maybe
Stressors	Yes	Yes
Energy production	Yes	No
Genetics	Yes	Yes
Hormonal changes	No	Yes
Chronic pain	No	Yes
Sleep deprivation	No	Yes
Mood disorders	No	Yes

Symptoms of Chronic Fatigue Syndrome vs. Fibromyalgia

ME/CFS and fibromyalgia have a lot of symptoms in common. But each one has distinguishing symptoms that help tell them apart.

Both conditions can involve dozens of symptoms.

ME/CFS Symptoms

The most common and prominent symptoms of ME/CFS are:

• Fatigue that doesn’t go away with rest
• Unrefreshing sleep
• Post-exertional malaise/exercise intolerance (an increase in symptoms after even light exertion)
• Cognitive dysfunction (“brain fog”), involving memory and learning problems
• Chronic, body-wide pain (in some people)
• Orthostatic intolerance (dizziness upon standing due to abnormal drops in blood pressure)
• Flu-like symptoms, including frequent sore throat and low-grade fever
• Sensitivities/intolerances to allergens, sensory input (noise, light), temperatures, food, medications, chemical odors

Less common symptoms vary from person to person and may include:

• Dry mouth and dry eyes
• Muscle twitching
• Recurrent infections
• Anxiety or irritability
• Irregular heartbeat
• Shortness of breath

Overlapping conditions that are sometimes considered symptoms include:

• Depression
• Endometriosis (uterine tissue grows outside the uterus)
• Irritable bowel syndrome (IBS, intestinal disorders)
• Premenstrual syndrome (PMS, which affects a person's emotions, moods, and body before a menstrual period begins)
• Tinnitus (ringing in the ears)

Fibromyalgia Symptoms

The primary symptoms of fibromyalgia are:

• Chronic, widespread pain
• Abnormal pain types
• Fatigue
• Unrefreshing sleep
• Cognitive dysfunction (“fibro fog”) involving memory and learning problems
• Digestive problems

Other fibromyalgia symptoms vary greatly and can include:

• Headaches and migraines
• Dizziness, vertigo, fainting
• Sensitivity to temperature, humidity, weather changes
• Sensitivities/intolerances to allergens, sensory input (noise, light), temperatures, food, medications, chemical odors
• Abdominal cramps
• Indigestion
• Boating
• Anxiety, irritability, and mood swings
• Extremely painful periods
• Premature menopause (menstrual periods stop for 12 months and beyond before the typical age)

Overlapping conditions that are sometimes considered symptoms include:

• Depression
• IBS
• Insomnia (poor sleep)
• Interstitial cystitis (painful bladder)
• Myofascial pain syndrome (chronic pain disorder)
• Obstructive sleep apnea (pauses in breathing during sleep)
• Restless legs syndrome (causes an uncontrollable urge to move the legs)

Diagnosing Chronic Fatigue Syndrome and Fibromyalgia

ME/CFS and fibromyalgia are both diagnoses of exclusion, which means:

• They don’t have objective lab or imaging tests.
• Other possible conditions must be ruled out.
• Multiple factors must be interpreted to come up with an answer.

This process can take a long time. You may have to push your healthcare provider to keep searching or to give you a referral.

Diagnosing ME/CFS

General practitioners usually end up diagnosing ME/CFS. That’s because no medical specialty has “claimed” it. This can complicate the diagnostic process.

To diagnose chronic fatigue syndrome, healthcare providers use: 

• Your symptoms
• A physical exam
• Blood tests such as complete blood count (CBC) and inflammatory markers to rule out other conditions
• Questionnaires that gauge symptoms, sleep, mental fatigue, and pain

The diagnostic criteria for ME/CFS include:

• Six months (or more) of profound, unexplained fatigue
• Post-exertional malaise lasting more than 24 hours after mental or physical exertion
• Unrefreshing sleep, being tired despite significant rest, other sleep disturbances such as an inability to fall asleep or stay asleep
• Either brain fog or orthostatic intolerance

Diagnosing Fibromyalgia

Fibromyalgia is often diagnosed by general practitioners, rheumatologists, and neurologists. 

Historically, it’s been classified as rheumatological, like arthritis. It’s now known that fibromyalgia involves a lot of neurological (brain and nervous system) abnormalities.

To diagnose fibromyalgia, they look at: 

• Your symptoms
• A physical exam
• Blood tests and possibly imaging to rule out other conditions
• Questionnaires that gauge pain and other symptoms

Fibromyalgia diagnostic criteria include evaluating:

• How widespread your pain is and what your other symptoms are like
• Whether symptoms have persisted at the same level for at least three months
• Whether there are any other explanations for the symptoms

Along with excluding other possible diagnoses, healthcare providers use two questionnaires to look for fibromyalgia. They’re the Widespread Pain Index (WPI) and Symptom Severity (SS) Scale.

The WPI looks at where you have pain. It includes 19 sites around the body, such as:

• Jaw, left and right
• Neck
• Shoulder girdle, left and right
• Upper arm, left and right
• Lower arm, left and right
• Upper back
• Lower back
• Chest
• Abdomen
• Hip/buttock/upper thigh, left and right
• Upper leg, left and right
• Lower leg, left and right

You get one point for every location where you have pain.

The SS scale evaluates four key symptoms. You score each one from 0 (no symptoms) to 3 (severe symptoms). They are:

• Fatigue
• Unrefreshing sleep
• Cognitive symptoms (trouble concentrating, confusion, disorientation, impaired comprehension)
• Somatic symptoms (physical sensations like pain, dizziness, nausea, fainting, or bowel disorders)

The maximum score is 12.

You can be diagnosed with fibromyalgia if you have:

• A WPI score of 7 or higher AND and SS score of 5 or higher
• Or, a WPI score between 3 and 6 and an SS score of 9 or higher
• And no other condition that could be responsible for symptoms

This can be a time-consuming process. Not all healthcare providers are comfortable diagnosing fibromyalgia. That means you may need to push for tests or a referral to a specialist.

Can You Have Both Chronic Fatigue Syndrome and Fibromyalgia?

You can have both chronic fatigue syndrome and fibromyalgia. In fact, many people do.

These conditions are considered “cousins,” of a sort. They belong to the same family of illnesses, which is called central sensitivity syndromes.

The symptoms are extremely similar. So, it can be difficult to tell if you have just one or both of these conditions.

Until there’s better diagnostic testing, it may sometimes be impossible to tell if you have both. It may never even be clear which one you have, either, depending on your specific mix of symptoms.

Fortunately, the treatments are similar. So, you may get the right treatments even if you’re not correctly diagnosed.

Treating Chronic Fatigue Syndrome and Fibromyalgia

There’s no standard treatment for ME/CFS or fibromyalgia. Most people end up with multiple types of treatment. It can take a lot of trial and error to come up with a good treatment regimen.

Types of treatment include:

• Medications
• Therapies
• Complementary and alternative medicine (CAM)
• Supplements
• Lifestyle changes

Treating ME/CFS

Nothing is proven to treat or cure ME/CFS. Studies are mixed on what helps.

So far, the Food and Drug Administration (FDA) hasn’t approved any drugs for treating ME/CFS. Many medications are used off-label (without official approval). They include:

• Antimicrobials: Target pathogens (including viruses, bacteria, and fungi) that may be involved in ME/CFS, which include Ampligen (rintatolimod), Valcyte (valganciclovir)
• Antidepressants: Target neurotransmitters (brain chemicals) that are dysregulated in ME/CFS, such as Cymbalta (duloxetine), Prozac (fluoxetine), Zoloft (sertraline)
• Antianxiety drugs: For those with anxiety issues, including Xanax (alprazolam), Ativan (lorazepam)
• Painkillers: Ranging from over-the-counter (OTC) or prescription anti-inflammatories to opioid painkillers, such as Advil/Motrin (ibuprofen), Aleve (naproxen), Relafen (nabumetone), Vicodin (hydrocodone/acetaminophen), OxyContin (oxycodone)
• Sleep drugs: To improve sleep duration and quality, including Klonopin (clonazepam), Lunesta (eszopiclone), Ambien (zolpidem)

Topical pain relievers like BioFreeze and Tiger Balm are commonly used, as well.

Therapies

Some therapies are controversial when it comes to ME/CFS. Two historically common ones are:

• Cognitive behavioral therapy (CBT): A type of talk therapy that addresses negative thoughts and habits and how to replace them with healthier behaviors.
• Graded exercise therapy (GET): Controlled exercise that attempts to build exercise tolerance.

These treatments used to be recommended as first-line treatments, despite little evidence showing them to be effective. A major flaw in this treatment approach is that it doesn't address known physiological abnormalities of the disease.

In fact, the theory behind these treatments holds that ME/CFS involves false beliefs, being out of shape, and having an irrational aversion to exercise. These beliefs are not supported by research or the experiences of people with ME/CFS.

Some studies estimated CBT and GET to benefit about 20% of people who tried them. Other estimates put it as low as 10%.

On top of that, many people with ME/CFS believe they've been harmed by these therapies. Researchers say about 10% of study participants reported being worse after CBT.

GET often triggers post-exertional malaise. That may have lasting physical and neurological effects.

If CBT and GET are recommended now, it's generally in addition to other treatments and focused on helping you adjust to the realities of life with chronic illness.

CAM Treatments

CAM treatments are common in ME/CFS because drug therapies are rarely effective enough on their own. They include:

• Acupuncture (practice that inserts thin, small needles into points around the body to provide stimulation)
• Massage (the act of rubbing and kneading the joints and muscles)
• Yoga, tai chi, or qigong (exercises that combine spiritual, physical, and mental components)
• Hypnotherapy (putting a person into a state of focused attention to increase suggestibility)
• Biofeedback (teaches people to control the way their bodies function)

Most of these have very little research to back them up.

Supplements

Supplements are also poorly researched but popular in people with ME/CFS. Many are in common use, including:

• 5-HTP
• Acetyl-L-carnitine
• CoQ10
• D-ribose
• Magnesium malate
• Melatonin
• Omega-3 (fish oil)
• Rhodiola rosea
• Turmeric
• Vitamin B12
• Vitamin D

Be sure your healthcare provider knows all the supplements you’re taking. Some may interact badly with prescription medications or have dangerous side effects.

Lifestyle Changes

Lifestyle changes and self-care are especially important in ME/CFS. Common recommendations include:

• Pacing
• Mild, appropriate levels of exercise that don’t trigger post-exertional malaise
• Improving sleep habits
• Deep breathing exercises
• Mindfulness
• A healthful diet

Treating Fibromyalgia

The FDA has approved three prescription drugs for fibromyalgia. Many others are used as well, with mixed results in both studies and real-world use.

Common medications for fibromyalgia include:

• Antidepressants: These medications target dysregulated neurotransmitters—the two FDA-approved antidepressants are Cymbalta (duloxetine) and Savella (milnacipran).
• Anti-seizure drugs: These drugs target dysregulated pain processing in the brain—one is FDA-approved, Lyrica (pregabalin), and another common one is Neurontin (gabapentin).
• Painkillers: These range from OTC or prescription anti-inflammatories to opioid painkillers, such as Advil/Motrin (ibuprofen), Aleve (naproxen), Relafen (nabumetone), Ultram (tramadol), Vicodin (hydrocodone/acetaminophen), OxyContin (oxycodone).
• Muscle relaxants: These target painful muscles and improve sleep, Flexeril (cyclobenzaprine), Zanaflex (tizanidine).
• Sleep drugs: To improve sleep duration and quality, Klonopin (clonazepam), Lunesta (eszopiclone), Ambien (zolpidem) may be prescribed.

Topical pain relievers are very common in people with fibromyalgia.

Therapies

Specialist therapies that may help with symptoms of fibromyalgia include:

• Talk therapy, including CBT: Helps with depression, anxiety, and the impact of chronic illness
• Physical therapy: Improves strength and flexibility to ease pain and improve function
• Occupational therapy: Focuses on energy conservation, pain management, stress management, and sleep hygiene

CAM Treatments

CAM treatments generally aren’t well studied for fibromyalgia. However, they’re quite popular in people with this condition. Common treatments include:

• Acupuncture
• Massage therapy, especially myofascial release
• Yoga, tai chi, or qigong
• Progressive muscle relaxation
• Biofeedback
• Medical cannabis

These approaches may help with symptoms not alleviated with drug treatments.

Supplements

While lacking conclusive evidence, many supplements are frequently used by people with fibromyalgia. Some common ones are:

• 5-HTP
• Acetyl-L-carnitine
• CoQ10
• L-theanine
• Magnesium malate
• Melatonin
• Omega-3 (fish oil)
• Rhodiola rosea
• SAMe 
• Turmeric
• Vitamin B12
• Vitamin D

Be sure to discuss supplements with your healthcare provider. Some may cause unwanted side effects or interact negatively with medications.

Lifestyle Changes

Lifestyle changes are considered paramount for managing fibromyalgia. Important ones include:

• Mild exercise at appropriate levels
• Pacing
• Improving sleep habits
• Deep breathing exercises
• Mindfulness meditation
• A healthy diet

Exercise is one of the most consistently beneficial fibromyalgia treatments, according to studies.

Summary

Chronic fatigue syndrome and fibromyalgia have more in common than not. That goes for causes, symptoms, diagnostic procedures, and treatments.

They do have some key differences, though.

A Word From Verywell

Having either of these conditions can force major changes in your life. It’s healthy to allow yourself to grieve for what you’ve lost to chronic illness.

With some effort, you may be able to find a treatment regimen that allows you to improve your quality of life. Some people even reach remission, when symptoms are minimal or absent.

So keep trying, and keep prodding your healthcare team for help, until you find what works for you.