Royal Free Disease

Last edited 08/2023 and last reviewed 09/2023

The terms myalgic encephalomyelitis (ME; or encephalopathy), chronic fatigue syndrome (CFS), CFS/ME and ME/CFS have all been used for this condition and are not clearly defined (1)

  • is little pathological evidence of brain inflammation, which makes the term 'myalgic encephalomyelitis' problematic

Chronic fatigue syndrome has been reported in epidemic and sporadic form since 1934 (2)

The terms myalgic encephalomyelitis (ME; or encephalopathy), chronic fatigue syndrome (CFS), CFS/ME and ME/CFS have all been used for this condition and are not clearly defined (1)

  • myalgic encephalomyelitis is classified under diseases of the nervous system in the SNOMED CT and ICD10 (G93.3)
  • many people with ME/CFS consider the name 'chronic fatigue syndrome' too broad, simplistic and judgemental. For consistency, the abbreviation ME/CFS
  • data from the UK Biobank suggest that there are over 250,000 people in England and Wales with ME/CFS, with about 2.4 times as many women affected as men
  • ME/CFS can affect people of all ages
  • the quality of life of people with ME/CFS is lower than that of many people with other severe chronic conditions, including multiple sclerosis and some forms of cancer
  • is unclear what causes ME/CFS
    • in many cases, symptoms are thought to have been triggered by an infection
    • it is not simple post-illness fatigue - it lasts longer and even minimal mental or physical activity can make symptoms worse
  • is no diagnostic test or universally accepted definition for ME/CFS

The key diagnostic features of ME/CFS are (3):

  • Post-exertional malaise/symptom exacerbation
    • whereby symptoms are amplified by physical and/or mental exertion with a delayed impact - later the same day, the next day, or even later. This is then followed by a slow recovery period. The amount of activity that provokes symptom exacerbation can be very minimal
  • Activity-induced muscle and brain fatigue
    • whereby there is a failure to create enough energy to continue with and sustain a wide range of physical and cognitive activities that would not normally cause any problem. There is no loss of motivation - as occurs in the chronic fatigue that often accompanies depression
  • Cognitive dysfunction
    • involving problems with short-term working memory, concentration and attention span, information processing and retrieval, planning and organising thoughts, word-finding ability and dysnomia. This is also known as 'brain fog'.
  • Unrefreshing sleep pattern may include hypersomnia (i.e excessive sleep requirements) in the early post-infection stage, fragmented sleep and myoclonic movements, or restless legs syndrome, later on
    • in more severe cases there may be a reversal of normal sleep rhythm (i.e, being awake at night but sleeping during the day). Excessive daytime sleepiness should raise the possibility of obstructive sleep apnoea - especially where there is snoring, early morning headaches and the person has a collar size above 16 inches (female) or 17 inches (male)
  • Autonomic nervous system dysfunction/dysautonomia involving orthostatic intolerance - an inability to sustain physical or mental activity whilst standing.
    • can produce symptoms such as lightheadedness, feeling faint, blurred vision, palpitations, sweating and nausea. In some cases there is postural hypotension (a fall in blood pressure from lying/sitting to standing resulting in dizziness or feeling faint) or postural orthostatic tachycardia syndrome (a significant rise in pulse rate on standing)
  • Other symptoms that are frequently reported include:
    • Pain
      • which can affect muscles (myalgia), joints (arthralgia) and nerves (neuropathic) but is minimal or not present at all in a minority of people. Pain is often difficult to alleviate with simple analgesics and may be accompanied by sensory disturbances/ paraesthesiae
    • Poor temperature control/thermoregulation
      • including increased sensitivity to hot and cold environments, sweating episodes, feeling feverish
    • On-going flu-like symptoms
      • including sore throats and tender glands without pathological enlargement
    • Intolerance or increased sensitivity to alcohol, chemicals and medications
      • especially psychotropic (antidepressant) drugs
    • Headaches of a new type or severity that may have a migrainous quality
    • Sensory disturbances including paraesthesiae ('pins and needles') and increased sensitivity to touch, noise (hyperacusis) and bright light (photophobia)
    • Digestive disturbances consistent with irritable bowel syndrome (i.e. abdominal pain, bloating, change in bowel habit) which may develop following the onset of ME/CFS and can be exacerbated by certain foods

Severity of ME/CFS

Definitions of severity are not clear cut because individual symptoms vary widely in severity and people may have some symptoms more severely than others. The definitions below provide a guide to the level of impact of symptoms on everyday functioning.

  • people with mild ME/CFS care for themselves and do some light domestic tasks (sometimes needing support) but may have difficulties with mobility. Most are still working or in education, but to do this they have probably stopped all leisure and social pursuits. They often have reduced hours, take days off and use the weekend to cope with the rest of the week.
Moderate ME/CFS
  • people with moderate ME/CFS have reduced mobility and are restricted in all activities of daily living, although they may have peaks and troughs in their level of symptoms and ability to do activities. They have usually stopped work or education, and need rest periods, often resting in the afternoon for 1 or 2 hours. Their sleep at night is generally poor quality and disturbed.
Severe ME/CFS
  • people with severe ME/CFS are unable to do any activity for themselves or can carry out minimal daily tasks only (such as face washing or cleaning teeth). They have severe cognitive difficulties and may depend on a wheelchair for mobility. They are often unable to leave the house or have a severe and prolonged after-effect if they do so. They may also spend most of their time in bed and are often extremely sensitive to light and sound.
Very severe ME/CFS
  • people with very severe ME/CFS are in bed all day and dependent on care. They need help with personal hygiene and eating, and are very sensitive to sensory stimuli. Some people may not be able to swallow and may need to be tube fed


  • fatigue in ME/CFS typically has the following components:
    • feeling flu-like, especially in the early days of the illness
    • restlessness or feeling 'wired but tired'
    • low energy or a lack of physical energy to start or finish activities of daily living and the sensation of being 'physically drained'
    • cognitive fatigue that worsens existing difficulties
    • rapid loss of muscle strength or stamina after starting an activity, causing for example, sudden weakness, clumsiness, lack of coordination, and being unable to repeat physical effort consistently

Principles of care for people with ME/CFS

Awareness of ME/CFS and its impact

Be aware that ME/CFS:

  • is a complex, chronic medical condition affecting multiple body systems and its pathophysiology is still being investigated

  • affects everyone differently and its impact varies widely - for some people symptoms still allow them to carry out some activities, whereas for others they cause substantial incapacity

  • is a fluctuating condition in which a person's symptoms can change unpredictably in nature and severity over a day, week or longer

  • can affect different aspects of the lives of both people with ME/CFS and their families and carers, including activities of daily living, family life, social life, emotional wellbeing, work and education.

Recognise that people with ME/CFS may have experienced prejudice and disbelief and could feel stigmatised by people (including family, friends, health and social care professionals, and teachers) who do not understand their illness. Take into account:

  • the impact this may have on a child, young person or adult with ME/CFS

  • that people with ME/CFS may have lost trust in health and social care services and be hesitant about involving them

Approach to delivering care

Health and social care professionals should:

  • take time to build supportive, trusting and empathetic relationships

  • acknowledge to the person the reality of living with ME/CFS and how symptoms could affect them

  • use a person-centred approach to care and assessment

  • involve families and carers (as appropriate) in discussions and care planning if the person with ME/CFS chooses to include them

  • be sensitive to the person's socioeconomic, cultural and ethnic background, beliefs and values, and their gender identity and sexual orientation, and think about how these might influence their experience, understanding and choice of management.

Recognise that people with ME/CFS need:
  • timely and accurate diagnosis so they get appropriate care for their symptoms

  • regular monitoring and review, particularly when their symptoms are worsening, changing or are severe

Explain to people with ME/CFS and their family or carers (as appropriate) that they can decline or withdraw from any part of their care and support plan and this will not affect access to any other aspects of their care. They can begin or return to this part of their plan if they wish to.

When working with children and young people with ME/CFS, ensure their voice is heard by:

  • taking a child-centred approach, with the communication focusing on them

  • discussing and regularly reviewing with them how they want to be involved in decisions about their care

  • taking into account that they may find it difficult to communicate and describe their symptoms and may need their parents or carers (as appropriate) to help them

  • recognising that they may need to be seen on more than 1 occasion to gain trust (with or without their parents or carers, as appropriate)

It is estimated that 1 in 4 adults diagnosed with ME/CFS are so severely affected that they are house-bound or bed-bound, with little functional capacity, needing 24-hour care (4)
  • this can last for months or years. In rare cases, the outcome has been fatal