Chronic Fatigue Syndrome Vs Fibromyalgia – Why You’re Always Tired

If you live with chronic pain and ongoing fatigue, there are two conditions that you’ve probably heard of: chronic fatigue syndrome (CFS) and fibromyalgia (FM).

It’s also likely that you have a lot of questions!

  • Is chronic fatigue syndrome the same illness as fibromyalgia?
  • What’s the difference between fibromyalgia and chronic fatigue syndrome?
  • How do I know if I have chronic fatigue syndrome or fibromyalgia?
  • Can you have both chronic fatigue syndrome AND fibromyalgia?
  • What the heck is myalgic encephalomyelitis (ME)?

This article will answer these questions and more, and help you figure out which condition you might have, and what to do about it.

The difference between fibromyalgia & CFS

First things first: chronic fatigue syndrome is not the same as fibromyalgia, although there can be a lot of similarities in the way they present. And it's not just "being very tired" either.

We all have nights when we don't get enough sleep and we feel sleepy, forgetful and irritable the following day1. But after a good night or two we wake up feeling rested and restored. For people with fatigue, that restful sleep doesn't come. Fatigue can then interrupt other parts of life. Sometimes, a vicious cycle occurs in which sleeplessness causes stress, which further impacts sleep, and for those who live with pain, that get thrown into the equation too2.

So, what are the symptoms of chronic fatigue syndrome versus fibromyalgia?

Chronic fatigue syndrome symptoms

Chronic fatigue syndrome (CFS) is sometimes called myalgic encephalomyelitis (my-AL-jik en-SEH-fuh-low-my-uh-LAI-tiss – it’s a real mouthful! But fortunately it is commonly abbreviated to ME), or you might see both terms together: myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).

Myalgic encephalomyelitis means muscle pain, and inflammation of the spinal cord and brain3. It’s a neurological disease that can impact multiple systems in the body, particularly the nervous and immune systems4, and it affects around 17 million people across the world5.

CFS is a chronic fatigue condition that is not the same as the general fatigue that comes with chronic pain. However, it is a common comorbidity to chronic pain conditions such as fibromyalgia, which means that it is a different condition but is present at the same time.

As with fibromyalgia, CFS symptoms can be varied in nature and severity. They include ongoing fatigue, pain, brain fog, sleep disturbances, trouble swallowing and post-exertional malaise (PEM) – sometimes referred to as a ‘crash’, ‘bust’, ‘relapse’ or ‘collapse’5. The feeling is pretty much the exhausted and wrinkled state a balloon is in once all the air has escaped. PEM is the extreme mental and physical fatigue that comes on after any amount of activity (even doing something very gentle) and is hard to recover from. It can also include other symptoms such as dizziness, headache, and sensitivity to stimuli such as light and sound6.

People who live with CFS can have mild, moderate or extreme symptoms, and symptom severity can fluctuate. People with mild symptoms may be able to care for themselves but lack the energy to do more than a few things each day, while at the severe end of the scale, someone may not be able to get out of bed and will need a lot of support3,5.

Fibromyalgia symptoms

Fibromyalgia is a chronic pain condition that affects around 160 million people worldwide. It also presents with fatigue, brain fog, and sleep disturbances, along with mood fluctuations and low mood, and sensitivity to external stimuli such as light and sound. People who live with fibro can have many other symptoms and comorbid conditions.

Causes of CFS & FM

Neither CFS or fibro have one clear cause, and for many people it is likely that several different factors work together to cause the condition.

For example, someone might have a genetic predisposition that compounds with an imbalance in the body, such as an immune system or digestive tract issue, plus some sort of event or trigger7.

The triggering cause of ME/CFS is often a viral infection, such as glandular fever, the herpes viruses, chickenpox or shingles, hepatitis, or meningitis8. COVID may also cause CFS, and many of the symptoms of Long-COVID match those of CFS3,9.

For some people, ME/CFS is sparked by a different infection or disease, such as salmonella, tuberculosis, or Lyme disease, or occasionally an injury or accident5.

However, it currently seems very unlikely that a stressful life event or emotional trauma can cause ME/CFS5. This is in direct contrast to fibromyalgia.

Fibromyalgia can also be set off by an infection, but for many people with fibro, their pain began following a traumatic event. That may be physical, such as an accident or a surgery, or emotional such as a bereavement. For some people, the start of their symptoms is related to pregnancy or childbirth10, which have both physical and emotional elements – even though this is usually a happy occasion, a new baby still comes with a lot of life changes and stress!

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Diagnosing chronic fatigue syndrome & fibromyalgia

Diagnosis for both CFS and fibro can be hard. Neither condition has strong biological markers that can be tested for without doubt and so they both tend to be diagnoses based on elimination of other possible conditions.

For a fibromyalgia diagnosis, doctors will ask for a medical history and will be looking for the presence of widespread pain that has been going on for at least three months and can’t be explained by anything else. Having some of the other hallmark symptoms of fibro, such as fatigue, brain fog, and sleep and mood disturbances also factor in.

For ME/CFS, the main symptom is extreme, unexplained fatigue and PEM. A doctor will also ask you about your sleep, and whether you struggle to sleep or wake up feeling unrefreshed, and 'brain fog, particularly if that impacts your ability to speak, recall words or numbers, concentrate and remember things. These symptoms should have been going on for at least six weeks3,11.

If you are hoping to get a CFS diagnosis or a fibromyalgia diagnosis, it’s a good idea to track your symptoms so that you can give your doctor a thorough history.

Is it fibro fatigue or CFS pain?

Okay, so if both fibromyalgia and ME/CFS can come with pain and fatigue, what’s the difference? Which one are you dealing with? What does fibromyalgia fatigue feel like? And what does CFS pain feel like?

Unfortunately, because fibromyalgia and chronic fatigue are related it is possible for CFS to be misdiagnosed as fibromyalgia, and vice versa. And you can have both chronic fatigue syndrome and fibromyalgia.

A simplistic way to consider it is that ME/CFS is chronic fatigue that can also come with pain, whereas fibromyalgia is chronic and widespread pain that can also present with fatigue. Which is your first and worst symptom? Pain or fatigue?

To dive in a little deeper, the main difference between CFS and fibro is PEM3,5. This is extreme fatigue that is disproportionate to the amount of activity done, and is often delayed, turning up hours or days later. It can take days, weeks or even longer to recover.

PEM is a key symptom of CFS and you can’t just “push through”, and in fact you shouldn’t try, because it won’t get better. This differs from fibro fatigue12, which tends to come on after someone has over exerted themself. People with fibro can usually build up their tolerance to activity by increasing the amount that they do (very gradually!) and pacing themselves. If you think you have fibro fatigue, it’s still important that you talk to your healthcare provider before you start increasing your activity level so that you know that what you are planning to do is safe for you. 

Symptoms that often come with CFS but are less common (but not unheard of!) with fibro include:

  • flu-like symptoms, also known as general malaise
  • a recurring sore throat, possibly with enlarged lymph nodes
  • trouble swallowing
  • difficulty speaking
  • sleep reversal – where you tend to be awake at night and asleep during the day, without trying
  • canker sores (mouth ulcers)6
  • blood pressure and heart rate regulation issues3.

Symptoms that often come with fibromyalgia but are less common (but not unheard of!) with CFS include:

  • psychological or emotional challenges such as depression and anxiety
  • restless leg syndrome
  • pain that moves around your body or seems to come and go
  • symptoms that get worse when you feel stressed. 

You might also hear the term “myofascial pain syndrome” (MPS). This is pain that comes from muscles and the surrounding connecting tissues (fascia) that hold everything in the body together. MPS is common in people who have musculoskeletal problems and because it usually relates to a specific injury or issue, the pain tends to remain localized. This is different to the pain of fibromyalgia, which is caused by central sensitization and therefore often moves around the body13.

What else could it be?

What if neither diagnosis feels right for you? There are other conditions14 that have similar symptoms, so talk with your doctor about these:

  • multiple sclerosis – an autoimmune disorder
  • Ehlers-Danlos Syndrome – a genetic disorder that includes pain, fatigue, and cognitive difficulties, and which presents with hypermobile joints (joints that bend further than they should)
  • Lyme disease – a bacterial infection
  • Behçet’s (beh-SHETS) disease – an autoimmune disease that presents with canker sores
  • Thyroid or pituitary issues, including Hashimoto’s disease
  • Lupus – an autoimmune disease, which often includes a rash on the face.

Treating fibromyalgia & chronic pain syndrome

There is no cure or single treatment for fibro or ME/CFS, and most treatments focus on reducing the various symptoms and their effects on a person’s life3.

Treatments that address pain relief, such as medications, physiotherapy, and heat packs can be helpful. For people with fibro, gentle movement is one of the best methods for lasting pain relief, and this can also help people who have CFS, although it is very important that they don’t push past their limits and spark PEM. Pacing15 is very important in managing both conditions.

Psychology or therapy is often very useful to assist with sleep and mood management15. For people with fibro this will be particularly helpful if stress is a trigger for them, or if emotional challenges are at the root of their condition.

People with either condition can benefit from a multidisciplinary approach that addresses sleep, stress, pacing, nutrition and gentle exercise. Depending on your specific symptoms you may benefit from other medicines or treatments, for example, people with ME/CFS who have cardiac complications.

Always speak with your healthcare providers about your specific situation. This is particularly important for any new symptoms or symptoms that change or worry you, and before you start or change any treatments.

Download the MoreGoodDays pain-management app from the App Store or Google Play for immediate access to more information about chronic pain and fatigue.