ME/CFS – Symptoms and diagnosis

The main symptom of ME/CFS is post-exertional malaise (PEM), also known as “activity intolerance" or "exertion intolerance.” This is where the symptoms get worse after physical or mental activity – sometimes even after gentle activity. Depending on how bad the ME/CFS is, the activity could be a short walk, a shower or a stressful conversation. Sometimes it takes a couple of days for PEM to develop, and it can last for hours, weeks or even months.

The symptoms of ME/CFS include:

• Extreme fatigue that you never used to have in the past, and that doesn’t really go away even if you rest. People with the illness are unable to go to work or school, or to meet up with friends and family – or they feel very drained afterwards if they do.
• Trouble getting a good night’s sleep. This includes problems falling asleep, waking up a lot during the night, and feeling just as tired in the morning as you were when you went to bed.
• Trouble concentrating and finding words, extremely slow thinking and poor short-term memory. You may also feel disoriented (“brain fog”).
• Circulation-related symptoms when sitting or standing, including dizziness, nausea, shakiness, an increased pulse or a rapid heartbeat. The medical term for this is “orthostatic intolerance.” It usually goes away when you lie down.
• Pain (for example, in the head, joints, muscles or lymph nodes).

Other possible symptoms of ME/CFS include:

• Flu-like symptoms, mild fever
• Increased sensitivity to light, smells and noise
• Problems regulating body temperature (for example, a tendency to feel cold or sweat)
• Poor blood circulation, with cold and blue fingers or toes
• Digestive problems
• Nausea
• Mental health problems like anxiety, depression and despair

Depending on the severity, ME/CFS is classified as follows:

• Mild: Here you can usually get by on your own. But many activities are much more difficult than before. You are less active in your free time and have to take more time off work. You often need the evenings and weekends to regain at least some of your strength.
• Moderate: It becomes more difficult to leave your home. Activities are very difficult and tend to trigger post-exertional malaise (PEM). The severity of your symptoms varies a lot. You can’t really work properly and need to take long breaks to rest. It is hard to get a good night's sleep.
• Severe: Apart from small tasks like brushing your teeth or hair, you can’t really do much without help. Your ability to concentrate is very limited. Pain may get worse, and sensitivity to light and noise may increase. You hardly ever make it out of your home and spend a lot of time in bed. You might need a wheelchair to get around. It takes a long time to recover from minor activities.
• Very severe: It is almost impossible to get out of bed. You need a lot of nursing care. You can no longer wash yourself, move or eat without assistance. Some people even have problems swallowing and have to be fed through a tube. You may also be extremely sensitive to sensory input (like light and noise).

About three quarters of people with ME/CFS have a mild or moderate form of the illness. Roughly one quarter are no longer able to leave their home; some are even bedridden.

Children and teenagers have similar symptoms to adults. Their symptoms can already get worse after gentle activity, too. Exhaustion, sleep problems, trouble concentrating and pain are common in children and teenagers as well. Their ME/CFS is more likely to go away than in adults.

It is harder to get the correct diagnosis, though. Younger children, in particular, describe and experience symptoms differently to adults. For instance, they might not think it’s unusual that they’re so exhausted if they can’t remember how things were before. Children and teenagers might also have more trouble “pacing” or managing their energy to make sure their symptoms don’t get worse.

It is common for children and teenagers with ME/CFS to be off school for a long time. Compared to children who don't have ME/CFS, they have fewer social contacts and aren’t as active in their free time. They often have extreme mood swings. Their school grades might drop as well because it's more difficult for them to focus. Many teenagers are anxious about their future and worry that they might get left behind, not get a good job and have to depend on others.

Experts from different parts of the world use different tools to diagnose ME/CFS. The tools are questionnaires about the symptoms, and you complete the questionnaire together with the doctor. The various diagnostic tools all have in common that they try to find out whether you have the following:

• Exhaustion ( fatigue) that doesn’t really go away when you rest, and your symptoms get a lot worse even after gentle physical or mental activity (post-exertional malaise, PEM).
• You also have other symptoms like sleep problems, trouble concentrating, pain or circulation-related symptoms (such as dizziness or a rapid heartbeat). The main difference between these diagnostic tools is what other symptoms they include.
• The symptoms have already lasted for more than 3 to 6 months.
• No other cause has been found.

It takes quite a lot of time and carefully conducted tests to diagnose ME/CFS with a fair amount of reliability. So a lot of patience is needed.

There is no one medical test for the diagnosis of ME/CFS. So various diagnostic tests and examinations are used if someone has symptoms that could be caused by ME/CFS. The standard approaches include:

• Assessment of medical history: Your doctor will ask about past and existing illnesses, how severe your symptoms are, and how they’re affecting you. It is particularly important to find out whether you have post-exertional malaise (PEM).
• Physical examination
• Checking for circulation-related symptoms after standing up (Schellong test)
• Blood tests and perhaps urine tests

A test to check your grip strength can be useful too. This involves squeezing the spring of a special measuring device with your hand as hard as you can. The device measures how much your muscle strength decreases due to exertion. Sometimes other examinations like ECGs, x-rays and computed tomography (CT) scans are done as well – mainly to detect or rule out other things that could be causing the symptoms.

It can also be helpful to keep a symptom diary where you make a note of what you’ve been doing and when the different symptoms occur.

The symptoms of ME/CFS are sometimes similar to the symptoms of other illnesses. Those illnesses should be ruled out before ME/CFS is diagnosed. They include, in particular:

• Chronic infections like hepatitis or Lyme disease
• Thyroid disease
• Gastrointestinal disorders (in the stomach and bowel) like celiac disease or Crohn’s disease
• Mental health disorders like depression or anxiety
• Neurological (nerve) disorders like multiple sclerosis or severe muscle weakness
• Autoimmune diseases like rheumatism or Sjögren’s syndrome
• Cancer
• Anemia
• Side effects of medications like antidepressants
• Sleep problems like sleep apnea
• Chronic pain disorders
• Harmful drug or alcohol consumption

ME/CFS can occur together with these conditions too.

People who have had COVID sometimes develop symptoms that are similar to (or even the same as) those of ME/CFS. They include extreme exhaustion, a lack of energy and concentration problems that continue even months after the infection first started. When this set of symptoms lasts longer than four weeks, it is considered to be “long COVID.” According to the World Health Organization (WHO), you have "post-COVID" if the symptoms last longer than twelve weeks, and there is no known possible explanation other than a COVID-19 infection.

Sometimes people who have these symptoms are diagnosed with ME/CFS. It is still not exactly clear how ME/CFS and post-COVID differ, and what they have in common.