Epidemic neuromyasthenia


Epidemic neuromyasthenia


Chronic fatigue syndrome (CFS) causes persistent fatigue (exhaustion) that affects everyday life and doesn't go away with sleep or rest. 

CFS is also known as ME, which stands for myalgic encephalomyelitis. Myalgia means muscle pain and encephalomyelitis means inflammation of the brain and spinal cord. Both CFS and ME are commonly used terms (see box on this page).

Sometimes the term 'myalgic encephalopathy' is used. Encephalopathy means a condition that affects brain function.

CFS is a serious condition that can cause long-term illness and disability, but many people – particularly children and young people – improve over time.


Who is affected

It is estimated that around 250,000 people in the UK have CFS.

Anyone can get CFS, although it is more common in women than in men. It usually develops in the early 20s to mid-40s. Children can also be affected, usually between the ages of 13 and 15. 

How it affects quality of life

Most cases of CFS are mild or moderate, but up to one in four people with CFS have severe symptoms. These are defined as follows: 

Mild: you are able to care for yourself, but may need days off work to rest. 

Moderate: you may have reduced mobility, and your symptoms can vary. You may also have disturbed sleep patterns, and need to sleep in the afternoon.

Severe: you are able to carry out minimal daily tasks, such as brushing your teeth, but you have significantly reduced mobility. You may also have difficulty concentrating.


Why it happens

It is not known exactly what causes CFS.

Various theories have been suggested, including:

a viral infection

problems with the immune system

an imbalance of hormones

psychiatric problems, such as stress and emotional trauma

Some people are thought to be more susceptible to the condition due to their genes, as the condition is more common in some families.

More research is needed to confirm exactly what causes the condition.


How it is diagnosed

There are specific guidelines issued by the National Institute for Health and Care Excellence (NICE) about the diagnosis and management of CFS.

NICE says that a diagnosis of CFS should be considered if you meet specific criteria regarding your fatigue (for example, it can't be explained by other conditions) and if you have other symptoms too, such as sleeping problems or problems thinking and concentrating.

The diagnosis can then be confirmed if these symptoms are experienced for several months.


How it is treated

There is no cure for CFS, so treatment aims to reduce the symptoms. Everyone with CFS responds to treatment differently, so your treatment plan will be tailored to you.

Some of the main treatments include:

cognitive behavioural therapy (CBT)

a structured exercise programme called graded exercise therapy

medication to control pain, nausea and sleeping problems

Treatments such as these can help improve CFS in most cases, although some people do not make a full recovery. It is also likely there will be periods when symptoms get better or worse.


Chronic fatigue syndrome (CFS)

Dr Charles Shepherd, medical adviser to the ME Association, and who has ME, describes the symptoms, diagnosis and treatments for ME, also known as chronic fatigue syndrome.

Media last reviewed: 19/03/2013

Next review due: 19/03/2015


CFS or ME?

There is some debate over whether the term chronic fatigue syndrome (CFS) or myalgic encephalomyelitis (ME) should be used.

Chronic fatigue syndrome (CFS) is the term often used and preferred by doctors because there is little evidence of brain and spinal cord inflammation, as the term ME suggests. ME is also thought to be too specific to cover all the symptoms.

Myalgic encephalomyelitis (ME) is the term preferred by some people who feel that CFS is too general and does not reflect the severity and different types of fatigue. It also highlights the fact that fatigue is not the only symptom.


Symptoms of chronic fatigue syndrome 

The symptoms of chronic fatigue syndrome (CFS) vary from person to person and there are often periods when they are better or worse.

There may be times when your symptoms improve and you'll be able to do many normal, everyday activities. However, at other times your symptoms may flare up and get worse, affecting your daily life.



The main symptom of CFS is persistent physical and mental fatigue (exhaustion). This does not go away with sleep or rest and limits your usual activities.

Most people with CFS describe this fatigue as overwhelming, and a different type of tiredness from what they have experienced before.

Exercising can make symptoms worse. This is called post-exertional malaise, or 'payback'. The effect of this is sometimes delayed – for example, if you were to play a game of sport, the resulting fatigue may not develop for a few hours afterwards, or even the next day.

People with severe CFS are unable to do any activities themselves or can only carry out simple daily tasks, such as brushing their teeth. They are sometimes confined to their bed and are often unable to leave their house. 


Other symptoms

There are other common symptoms as well as fatigue, although most people do not have all of them. They include:

muscular pain, joint pain and severe headaches

poor short-term memory and concentration, and difficulty organising thoughts and finding the right words ('brain fog')

painful lymph nodes (small glands of the immune system)

stomach pain and other problems similar to irritable bowel syndrome, such as bloating, constipation, diarrhoea and nausea

sore throat

sleeping problems, such as insomnia and feeling that sleep is not refreshing

sensitivity or intolerance to light, loud noise, alcohol and certain foods

psychological difficulties, such as depression, irritability and panic attacks

less common symptoms, such as dizziness, excess sweating, balance problems and difficulty controlling body temperature

Causes of chronic fatigue syndrome 

Exactly what causes chronic fatigue syndrome (CFS) is unknown, but there are several theories.

Some experts think a viral infection such as glandular fever can trigger the condition. Tiredness is normal after a viral infection, but this does not explain why symptoms persist and get worse in CFS.

Also, many cases of CFS do not start after an infection and this theory does not explain why the condition sometimes develops gradually.

Other suggested causes of CFS include:

problems with the immune system 

a hormone imbalance

psychiatric problems – some cases have been linked to mental exhaustion, stress, depression and emotional trauma

genes – some people may have an inherited tendency to develop CFS, as it is more common in some families

traumatic events - some cases have been linked to events such as surgery or a serious accident

It is possible that CFS is caused by a combination of factors. Further research is necessary to confirm the cause(s).


Debate over classification

The World Health Organization (WHO) has classified CFS as a chronic (long-term) neurological condition and this classification has been accepted by the Department of Health.

However, the WHO’s decision remains controversial and is not accepted by everyone working in the field.

Members of the team of health professionals who drew up the National Institute of Health and Care Excellence (NICE) guidelines for CFS could not agree that this classification is the right decision, and 84% of members of the Association of British Neurologists surveyed in 2011 said they did not view CFS as a neurological condition.


Diagnosing chronic fatigue syndrome 

There is no test for chronic fatigue syndrome (CFS), but there are clear guidelines to help doctors diagnose it.

It can take a long time for the condition to be diagnosed, as other conditions that cause similar symptoms need to be ruled out first. Therefore, you may be given some advice about managing your symptoms before a diagnosis is confirmed (see treating CFS for more information).

If you see your GP about persistent and excessive fatigue, they will ask you about your medical history and may carry out a physical examination.

You may have blood tests, urine tests and scans to rule out other conditions, such as anaemia (lack of red blood cells), an underactive thyroid gland or liver and kidney problems.


 NICE guidelines for diagnosing CFS 

Guidelines released in 2007 from the National Institute for Health and Care Excellence (NICE) state that doctors should consider diagnosing CFS if a person has fatigue and all of the following apply:

it is new or had a clear starting point (it has not been a lifelong problem)

it is persistent and/or recurrent

it is unexplained by other conditions

it substantially reduces the amount of activity someone can do

it feels worse after physical activity

The person should also have one or more of these symptoms:

difficulty sleeping, or insomnia

muscle or joint pain without inflammation 


painful lymph nodes that are not enlarged

sore throat

poor mental function, such as difficulty thinking

symptoms getting worse after physical or mental exertion

feeling unwell or having flu-like symptoms

dizziness or nausea

heart palpitations, without heart disease

This diagnosis should be confirmed by a clinician after other conditions have been ruled out, and the above symptoms have persisted for at least four months in an adult and three months in a child or young person.


 Chronic fatigue syndrome or PoTS? 

It's likely that some people diagnosed with chronic fatigue syndrome will actually have postural tachycardia syndrome (PoTS).

PoTS is an abnormal increase in heart rate after sitting or standing up, which typically causes dizziness, fainting, sweating and other symptoms.

 Treating chronic fatigue syndrome  

There is no cure for chronic fatigue syndrome (CFS), but treatments can help relieve the symptoms.

The treatments used will depend on how CFS affects you. Early diagnosis, medication to control certain symptoms and lifestyle measures can all help (see below).

CFS may last a long time, but treatment often helps improve the symptoms.


 Treatment programme 

The National Institute for Health and Care Excellence (NICE) advises that an individual programme of treatment should be offered to you with the aims of:

maintaining and, if possible, extending your emotional and physical abilities

managing the physical and emotional effects of your symptoms 

You may be offered the treatments explained below, but remember: what works for one person may not work for you.

The benefits and risks of each treatment should be explained to you, as some treatments could make your symptoms worse. Both you and the healthcare professional treating you will decide on your treatment programme. You have the right to refuse or withdraw from any treatment recommended for you.

If your symptoms continue to get worse for several days after trying a certain treatment, or if your symptoms are particularly severe, contact the healthcare professional who is treating you. It may be necessary to amend your treatment programme.

Cognitive behavioural therapy

Cognitive behavioural therapy (CBT) is a type of therapy that can help you manage CFS by changing the way you think and behave. It's often used as a treatment for a range of health conditions.

CBT aims to help reduce the severity of your symptoms and the distress associated with CFS. It works by breaking down overwhelming problems into smaller parts and by breaking the negative cycle of interconnected thoughts, feelings, physical sensations and actions.

Ideally, your CBT therapist will have experience in dealing with CFS and treatment will be offered on a one-to-one basis. The treatment will be tailored to your needs and may include some of the following:

helping you to accept your diagnosis

challenging thoughts that could prevent your symptoms improving

trying to increase your sense of control over your symptoms

The use of CBT does not mean CFS is considered to be a psychological condition. It is often used as a treatment for a variety of long-term conditions, such as cancer and rheumatoid arthritis.


Graded exercise therapy

Graded exercise therapy (GET) is a structured exercise programme that aims to gradually increase how long you can carry out a physical activity. This will usually involve aerobic exercise (exercise that raises your heart rate) such as swimming or walking. You will have your own exercise programme adapted to your own physical capabilities.

GET should only be carried out by a trained specialist with experience in CFS and, if possible, should be offered on a one-to-one basis. After finding your 'baseline (what you can comfortably do already) in the exercise, you will gradually increase:

the length of time that you do the exercise

the exercise intensity

As part of your exercise programme, you and your therapist will set goals, such as being able to walk to the shops or carry out some gardening. It may take weeks, months or even years for you to achieve these goals, but it is very important that you do not exceed the exercise duration and intensity set for you.


Activity management

Activity management is another aspect of your treatment programme that involves setting individual goals and gradually increasing your activity levels. You may be asked to keep a diary of your current activity and rest periods to establish your baseline. Activities can then be gradually increased in a way that you find manageable.



There is no medication available that can treat CFS specifically, but different medicines may be used to relieve some of the symptoms of the condition.

Over-the-counter painkillers can help ease any muscle pain, joint pain and headaches you may have. Stronger painkillers can also be prescribed by your GP, although they should only be used on a short-term basis.

If you have chronic (long-term) pain, you may be referred to a pain management clinic. There are about 300 of these across the UK, mostly located in hospitals.

Antidepressants can be useful for people with CFS who are in pain or having trouble sleeping. Amitriptyline is a low-dose tricyclic antidepressant that may be prescribed. Amitriptyline is not suitable for everyone – for example, it may not be suitable if you have a history of heart problems. It can also cause side effects such as a dry mouth, blurred vision, dizziness and drowsiness.

If you experience severe nausea due to CFS, you may benefit from a type of medication called an anti-emetic.


Lifestyle advice

As well as these treatments, you may find the lifestyle advice below helpful.


Pacing may be a useful way of controlling CFS symptoms. It involves balancing periods of activity with periods of rest.

Pacing means not overdoing it or pushing yourself beyond your limits. If you do, it could slow down your progress in the long term. Over time, you can gradually increase your periods of activity, while making sure they are balanced with periods of rest.

Learning how to make the most of your energy helps increase the amount that you can do. However, you may need to arrange your daily and weekly activities around when you can be active and when you need to rest.

If you pace your activities at a level that is right for you – rather than rushing to do as much as possible in a short space of time – you may be able to make steady progress.

However, it is important to note that there are some uncertainties about pacing. There is insufficient evidence on the benefits or harm of this treatment, although it is often recommended for CFS.


Other self-help techniques

The following recommendations may also help:

avoid stressful situations

avoid alcohol, caffeine, sugar and sweeteners

avoid any food and drink that you are sensitive to

eat small, regular meals to help reduce any nausea

spend time relaxing

try not to sleep or nap excessively, as this does not help and may make any sleeping problems worse


A relapse is when your symptoms get worse for some time, leaving you unable to function at the level you previously managed.

Relapses are a common part of CFS and can be caused by a number of factors, such as an infection or an unplanned activity. Sometimes there is no clear cause.

The healthcare professionals treating you can help you manage your relapse, by:

including more breaks with your current levels of activities

teaching you relaxation and breathing techniques

encouraging you to be optimistic about your recovery

Over time and with treatment, many people with CFS begin to show improvement.