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 What is chronic fatigue syndrome?

Chronic fatigue syndrome (CFS), also referred to as myalgic encephalomyelitis (ME), is a condition that causes long-term tiredness (fatigue) and other symptoms which are not caused by any other known medical condition.

  • CFS stands for chronic fatigue syndrome. Chronic means persistent or long-term.

  • ME stands for myalgic encephalomyelitis. Myalgic means muscle aches or pains. Encephalomyelitis means inflammation of the brain and spinal cord.

There is no test to diagnose the condition. The diagnosis is made in people who have a certain set of symptoms (which can vary in their type and severity).

What are the symptoms of chronic fatigue syndrome?

The onset of chronic fatigue syndrome symptoms can be fairly sudden (over a few days or so), or more gradual. CFS should be suspected if the following symptoms are not explained by any other condition, and persist for a minimum of six weeks in adults, or four weeks in children and young people:

  • Extreme tiredness (fatigue) that is worsened by activity, but is not caused by excessive exertion, and is not significantly relieved by rest.

  • Post-exertional malaise (PEM): feeling unwell with no energy after activities, with a worsening of symptoms that:

    • Often doesn't start until hours or days after the activity.

    • Is much greater that you would expect for that particular activity.

    • Has a prolonged recovery time that may last hours, days, weeks or longer.

  • Unrefreshing sleep or sleep disturbance, which may include:

    • Feeling exhausted, feeling flu-like and stiff on waking.

    • Broken or shallow sleep, altered sleep pattern or excessive daytime sleepiness (hypersomnia).

  • Difficulties with conscious mental activities, such as thinking, reasoning, or remembering (cognitive difficulties), sometimes described as 'brain fog'. This may include:

    • Problems finding words or numbers.

    • Difficulty in speaking.

    • Slow to respond.

    • Short-term memory problems.

    • Difficulty concentrating or multitasking.

  • Inability to engage fully in work, educational, social or personal activities.

The diagnosis can only be confirmed after three months of persistent symptoms, but only if the symptoms cannot be explained by any other condition.

Other chronic fatigue syndrome symptoms

Other symptoms that may be associated with CFS/ME include:

  • Dizzinesspalpitationsfaintingnausea on standing or sitting upright from a lying position.

  • Increased sensitivity to temperature, causing increased sweating, chills, hot flushes or feeling very cold.

  • Twitching and other abnormal uncontrolled body movements.

  • Flu-like symptoms, including sore throat, tender glands, nausea, chills or muscle aches.

  • Intolerance to alcohol, or to certain foods or chemicals.

  • Increased sensitivities, including to light, sound, touch, taste and smell.

  • Pain, including pain on touch, muscle pain, headaches, eye pain, tummy (abdominal) pain, or joint pain.

Severity of chronic fatigue syndrome symptoms

Symptoms vary widely in severity and people may have some symptoms more severely than others. However, the following definitions are provided by NICE to provide a guide to the level of impact of symptoms on everyday functioning:

Features of mild chronic fatigue syndrome

These include:

  • You are able to care for yourself and do some light domestic tasks (sometimes needing support) but may have difficulties with mobility.

  • You are usually still able to work or attend education, but to do this you have probably stopped all leisure and social pursuits.

  • You often have reduced hours, take days off and use the weekend to cope with the rest of the week.

Features of moderate chronic fatigue syndrome

These include:

  • You have reduced mobility and are restricted in all activities of daily living.

  • However you may have peaks and troughs in your level of symptoms and ability to do activities.

  • You have usually stopped work or education, and need rest periods, often resting in the afternoon for one or two hours.

  • Your sleep at night is generally of poor quality and disturbed.

Features of severe chronic fatigue syndrome
These include:

  • You are unable to do any activity for yourself, or you can carry out minimal daily tasks only (such as face washing or cleaning teeth).

  • You have severe cognitive difficulties and may depend on a wheelchair for mobility.

  • You are often unable to leave the house or you have a severe and prolonged after-effect if you do so.

  • You may also spend most of your time in bed and are often extremely sensitive to light and sound.

Features of very severe chronic fatigue syndrome
These include:

  • You are in bed all day and dependent on care.

  • You need help with personal hygiene and eating, and are very sensitive to sensory stimuli.

  • Some people with very severe CSF/ME may not be able to swallow and may need to be tube fed.

How is chronic fatigue syndrome diagnosed?

There is currently no test to diagnose chronic fatigue syndrome and it is recognised from your symptoms alone. However, some tests are usually done to rule out other causes of your tiredness (fatigue) or other symptoms. For example, blood tests may be done to rule out anaemia, an underactive thyroid gland, liver problems and kidney problems.

What causes chronic fatigue syndrome?

The cause of chronic fatigue syndrome is not known. There are various theories but none has been proved. A popular theory is that a viral infection may trigger the condition. It is well known that tiredness (fatigue) is a symptom that can persist for a short time following certain viral infections. For example, infection with the glandular fever virus, Covid 19 (Long Covid), the influenza virus can cause fatigue for several weeks after other symptoms have gone. However, most people recover within a few weeks from the tiredness that follows known viral infections.

Even if a viral infection is a trigger of CFS, it is not clear why symptoms persist when there is no evidence of persisting infection. Also, the symptoms of many people with CFS do not start with a viral infection.

Factors that are thought to contribute to some people developing CFS include:

  • Inherited genetic susceptibility (it is more common in some families).

  • Exhaustion and mental stress.

  • Depression.

  • A traumatic event such as bereavement, divorce or redundancy.

It is hoped that research will clarify the cause (or causes) of CFS in the future.

What is the treatment for chronic fatigue syndrome?

There is no known cure for chronic fatigue syndrome, although symptoms can be self-managed with support and advice. When CFS/ME is suspected, you should be given individual advice about managing your symptoms. This advice will include:

  • Not to use more energy than you feel you have. Try to manage your daily activity and do not 'push through' your symptoms.

  • Rest as you need to. This might mean making changes to your daily routine, including work, school and other activities.

  • Maintain a healthy balanced diet, with adequate fluid intake.


You should be referred to a physiotherapist or occupational therapist working in an CFS specialist team if you:

  • Have difficulties caused by reduced physical activity or mobility.

  • Feel ready to progress your physical activity beyond your current activities of daily living.

  • Would like to incorporate a physical activity or exercise programme into managing your CFS/ME.


Energy management

Each person has a different and fluctuating energy limit and you are the expert in judging your own limits.

A personalised physical activity or exercise programme should only be considered if you feel ready to progress your physical activity beyond your current activities of daily living or would like to include physical activity or exercise into managing your CFS/ME. Some people with CFS have found that energy management programmes can make their symptoms worse, some people find it makes no difference and others find them helpful.

An energy management plan uses a flexible approach that is tailored individually for you, so that activity is never automatically increased but is maintained or adjusted (upwards after a period of stability or downwards when symptoms are worse). Energy management can take weeks, months or sometimes even years to reach stabilisation or to increase tolerance or activity.

An energy management plan includes all types of activity (mental, physical, emotional and social) and takes into account your overall level of activity. It helps you learn to use the amount of energy you have while reducing your risk of post-exertional malaise or worsening your symptoms by exceeding your limits.

Any activity or exercise programme must be led by you, with support from a healthcare professional in an CFS specialist team. A physical activity or exercise programme should be overseen by a physiotherapist in an CFS specialist team.

The first step is to agree a sustainable level of activity, which may mean initially reducing activity. The plan should include periods of rest and activity. It is important to alternate and vary between different types of activity, and break activities into small chunks.

Exercise that is not part of a programme, such as going to the gym or exercising more, should be avoided, because this may worsen your symptoms. Graded exercise therapy in which you make fixed increases in the time spent being physically active is also not recommended.

Cognitive behavioural therapy

Cognitive behavioural therapy (CBT) should only be offered to help you manage your symptoms, improve your level of functioning and reduce the distress associated with having a chronic illness.

CBT for people with CFS aims to improve your quality of life and does not assume you have any 'abnormal' illness beliefs and behaviours that may be contributing to your CFS symptoms and difficulties.

CBT should aim to help you develop an understanding about the main difficulties and challenges you face, explore your understanding of your symptoms and illness, and so help you to manage your symptoms.

Severe or very severe CFS/ME

If you have severe or very severe CFS/ME, you will need more frequent reviews and increased support and care. You should also be referred:

  • To a physiotherapist or occupational therapist working in an CFS specialist team for support on developing energy management plans.

  • To a dietician with a special interest in CFS.

The process and pace of any CBT should be adjusted to meet your needs. This might include shorter, less frequent sessions and longer-term goals.

Flare-ups and relapse

Flare-ups and relapses can happen even if your symptoms are well managed. It is very important that you are given and agree individual advice on how to adjust your activity during a flare-up or relapse. This should include how to access review and support from a physiotherapist in an CFS specialist team. The time it takes to return to the level of physical activity varies from person to person.

A flare-up usually lasts a few days, and is a worsening of your symptoms beyond the normal day-to-day variation. Some flare-ups will develop into a relapse. For a flare-up:

  • Identify possible triggers, such as acute illness or overexertion, but there may be no clear trigger.

  • Temporarily reduce your activity levels, monitor symptoms, and do not return to usual activity levels until the flare-up has resolved.

A relapse is a more persistent and marked increase in your symptoms, needing substantial and sustained adjustment of your energy management. For a relapse:

  • Identify possible causes.

  • Reduce or stop some activities.

  • Increase the frequency or duration of rest periods.

  • Reassess energy limits to help stabilise your symptoms.

If you are unable to manage a flare-up, or a relapse cannot be managed using your planned self-management strategy, you should contact your named contact in your GP practice.

Management of chronic fatigue syndrome symptoms

Rest and sleep in CFS
Rest periods in the daily routine are part of management strategies for all people with chronic fatigue syndrome. Relaxation techniques at the beginning of each rest period can be helpful. Try to balance the need for rest during the day against how you are sleeping at night. Introduce changes to your sleep pattern gradually.

Physical functioning and mobility problems in CFS

Strategies to help maintain and prevent deterioration of your physical function and mobility need to be carried out in small amounts and spread out throughout the day. Strategies should include joint mobility, muscle flexibility, balance, postural and positional support, muscle function, bone health and cardiovascular health.

Care and support plans in relation to physical functioning and mobility may include bed mobility, moving from lying to sitting to standing, transferring from bed to chair, using mobility aids, walking, joint mobility, muscle stretching, muscle strength, balance, and going up and down stairs.

People with CFS may experience intolerance of changing position, such as when first standing up. 

Pain in CFS

Chronic pain is commonly associated with CFS. You may need referral to specialist pain services if appropriate.

People with chronic fatigue syndrome may be more intolerant of drug treatment. Therefore you may need to start medicines at a lower dose than usual, and then gradually increase the dose if you are able.

Dietary management and strategies for CFS
Adequate fluid intake and a well-balanced diet are essential. You may need to be referred to a dietician with a special


interest in CFS if you are:

  • Losing weight and at risk of malnutrition.

  • Gaining weight.

  • Following a restrictive diet.

Children and young people with CFS who are losing weight or have poor growth, or a restricted diet should be referred to a paediatric dietician with a special interest in CFS.

People with FS may be at risk of vitamin D deficiency, especially those who are housebound or bed-bound.

There is not enough evidence to support routinely taking vitamin and mineral supplements as a cure for CFS or for managing symptoms.

Review of CFS in primary care
Adults with CFS should be seen for a review of their care and support plan in primary care at least once a year. Children and young people with CFS should have a review of their care and support plan at least every six months. More frequent reviews may be needed, depending on your symptoms, and the effectiveness of any symptom management.

Each review should include:

  • Your condition, including any changes in your illness and the impact of this.

  • Your symptoms, including whether you have any new symptoms.

  • Your energy management plan and, if relevant, your physical activity or exercise programme.

  • Who is helping you and how they provide you with support.

  • Your psychological, emotional and social well-being.

  • Any future plans, such as considering any changes or if you have any challenges ahead.


Children and young people reviews should be carried out or overseen by a paediatrician with expertise in CFS.

What is the outlook (prognosis)?

The long-term outlook varies from person to person. Although some people recover or have a long period of remission, many will need to adapt to living with /CFS. The outlook is better in children and young people than in adults.

CFS 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 severe impacts on different aspects of the lives of people with CFS and their families and carers, including activities of daily living, family life, social life, emotional well-being, work and education.

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