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M.E. = Myalgic Encephalopathy/Encephalomyelitis
Myalgic = characteristic muscle symptoms. Encephalopathy = significant disorder of brain function.

Page Content:

Part 1: Timescale

Part 2: Making a Diagnosis

Part 3: Precipitating Factors for ME/CFS

Part 4: Diagnostic Delay and benefit from having an Early Diagnosis

Part 5: Specialist Referral

Part 6: Clinical History

Part 7: Differential Diagnosis

Part 8: Recently Diagnosed

Dr Charles Shepherd, Hon. Medical Adviser to the ME Association, explains how M.E. is diagnosed, in a short video that was made by ME/CVS Vereniging.

ME Association clinical and research guide

The information in this section has been taken from An Exploration of the Key Clinical Issues:

  • The 10th edition is a must-have for anyone who has been affected by – or has an interest in – Myalgic Encephalopathy/Encephalomyelitis (M.E.).
  • It’s undergone a thorough, 6,000-word revision, is up to date, fully-referenced, and contains 147, A4-size pages.
  • It features a thorough clinical evaluation and all relevant published research.
  • Written by Dr Charles Shepherd, Hon. Medical Adviser to the ME Association, and Dr Abhijit Chaudhuri, Consultant Neurologist, Essex Centre for Neurosciences, Clinical Issues is reviewed and revised on an annual basis.
  • You can purchase a copy from our online shop or by contacting head office on 01280 818964 (Monday-Friday, 9.30am to 3.00pm).

Free copy available for health professionals!

We have funds set aside in our medical education budget to provide free copies of our clinical and research guide to GPs and other health professionals. Contact us with the details on the phone number above, or send head office an email.

Part 1:


A short period of debility frequently follows many acute infections. However, when this persists beyond three or four weeks in a previously healthy individual, consideration should be given to the possible diagnosis of a post-infectious/viral fatigue syndrome.

There is collective evidence to suggest that appropriate management at this very early stage (i.e. addressing key symptoms and advising on a period of convalescence followed by gradual and flexible increases to physical and mental activities) may minimise long-term morbidity and severity.

Where symptoms persist beyond three months and the person concerned has been unable to resume a normal way of life, serious consideration should then be given towards making a provisional diagnosis of ME/CFS.

The timescale should be shorter in children and adolescents, and, where a child or adolescent has missed around 4 weeks of school, action must be taken to speed up the diagnostic process.

By four months, if symptoms still persist, the provisional diagnosis of ME/CFS should have normally been confirmed or excluded in adults.


It should normally be confirmed or excluded by three months in children and adolescents.


In clinical practice, six months should normally be viewed as the endpoint of the diagnostic process for ME/CFS.

Part 2:

Making a Diagnosis

A positive diagnosis of ME/CFS should be based on the characteristic clinical features that are almost always present – exercise-induced fatigue, post-exertional malaise/symptom exacerbation, cognitive dysfunction, orthostatic intolerance, on-going flu like symptoms and unrefreshing sleep – often in conjunction with other common symptoms.

At the same time, a thorough clinical evaluation involving history taking, physical examination and investigations should be carried out to exclude other medical and psychiatric conditions that can cause chronic fatigue and other ME/CFS-like symptoms.

The differential diagnosis of ME/CFS is considered in more detail below.

Tired all the time (TATT) is a potentially dangerous diagnosis. It avoids pinning down what is wrong – medically, mentally, socially – with a patient. Whilst TATT may have some merit while a patient is being assessed, it should not be used as a definitive final diagnosis.

Diagnostic criteria

There are a considerable number of diagnostic criteria for ME/CFS. Most have been designed for research rather than clinical purposes and stipulate that symptoms should have been present for six months or more.

Whilst this is acceptable for selecting patients for research, it should be possible in straightforward cases that follow an acute infection to start with a diagnosis of a post-viral fatigue syndrome and to then consider making a diagnosis of ME/CFS where symptoms persist beyond three months.

> Please refer to the discussion on diagnostic criteria on our previous page.

Part 3:

Precipitating Factors for ME/CFS

  • Some form of viral infection (e.g. flu-like, glandular fever, respiratory tract infection, viral hepatitis, meningitis) is the most common precipitating factor.
  • Non-viral infections such as Coxiella burnetii/Q fever (Ayres et al 1998) and bacterial meningitis can also precipitate ME/CFS.
  • Less commonly reported triggers include certain vaccinations (e.g. hepatitis B), toxins (e.g. ciguatera poisoning), pesticide exposure (organophosphates) and major stressful life events.
  • In a minority, there may not be an identifiable precipitating factor, and the onset may then be more gradual.

Part 4: 

Diagnostic Delay and benefit from having an Early Diagnosis

The aim should be to provide people with an early and accurate diagnosis. Unfortunately, many people are still waiting far too long before a diagnosis of ME/CFS is either considered or confirmed.

The most recent MEA website poll, which was carried out in February 2016, found that over 60% had waited a year or more for a diagnosis.


These results confirm that many doctors still lack the necessary knowledge or clinical experience to make, or even consider, a diagnosis of ME/CFS.

The importance of an early and accurate diagnosis is a key point that is continually being highlighted by patients. Evidence from other areas of chronic illness management indicates that early diagnosis labelling can minimize the psychosocial impact of an illness.

However, over the next two years, around 50,000 people will develop ME/CFS, and many will continue to experience prolonged uncertainty regarding diagnosis.

Making an early and accurate diagnosis of ME/CFS enables a comprehensive plan of management to be agreed with the patient. This should cover activity management, symptom relief, employment, education, etc.

Developing an agreed plan of appropriate management should prevent inappropriate or harmful approaches to management taking place – e.g. attempting to ‘work through fatigue’ – and should therefore reduce the risk of a more prolonged and severe illness occurring.

> We have produced a useful leaflet explaining the importance of early and accurate diagnosis and the process that should be adopted – including necessary testing to exclude other possible causes and symptoms that should be considered appropriate.

Part 5:

Specialist Referral

Where there is continuing uncertainty about the diagnosis, or management advice is deemed necessary, or if symptoms are severe, patients should be referred to a hospital based ME/CFS specialist service in secondary care.

If there is not a suitable ME/CFS specialist service nearby, the Countess of Mar has established through a House of Lords parliamentary question that people can be referred elsewhere to an NHS service or consultant of their choice (House of Lords Debate, 24 June 2014, Volume No. 754 col. WA149).

We try to maintain a registry of all the multidisciplinary hospital-based referral services for adults and children in the UK, but we cannot guarantee the details are accurate. Referral to specialist services should normally be sought via your GP in the first instance.

In 2015, we published the results of a large patient survey which examined the various management approaches to ME/CFS:

‘It is our hope that this new evidence might persuade the National Institute for Health and Care Excellence (NICE) to improve the current clinical guideline on ME/CFS (CG53), and provide clearer guidance to NHS specialist services and private health practitioners on ways in which illness management advice can be made more suitable for all those affected by this illness; thus, leading to improved patient reported outcomes.’

We concluded that:

  • Cognitive behavioural therapy (CBT) in its current delivered form should not be recommended as a primary intervention for people with ME/CFS.

An appropriate model of CBT – one that helps patients learn practical coping skills and/or manage co-morbid issues such as those listed above – could be employed, where appropriate, for ME/CFS as it is for other chronic physical illnesses such as multiple sclerosis, Parkinson’s disease, etc.; and we recommend all patients should have access to such courses as well as access to follow-up courses and/or consultations as and when required.

  • Graded exercise therapy (GET) should be withdrawn with immediate effect as a primary intervention for everyone with ME/CFS.

GET cannot be regarded as a safe and effective form of treatment for most people with ME/CFS. The fact that many people, including those who consider themselves severely affected, are being referred to specialist services for an intervention that makes them either worse or much worse is clearly unacceptable and in many cases dangerous.

  • Pacing was consistently shown to be the most effective, safe, acceptable and preferred form of activity management for people with ME/CFS and should therefore be a key component of any illness management programme.

The benefit of Pacing may relate to helping people cope and adapt to their illness rather than contributing to a significant improvement in functional status. Learning coping strategies can help make courses more appropriate to needs even if they do not lead to immediate or even longer-term improvement in symptoms. Importantly, it can prevent symptoms from becoming worse.

The NICE guideline on ME/CFS clearly states that:


‘Healthcare professionals should be aware that – like all people receiving care in the NHS – people with CFS/ME have the right to refuse or withdraw from any component of their care plan without this affecting other aspects of their care, or future choices about care.’


‘Healthcare professionals should recognise that the person with CFS/ME is in charge of the aims and goals of the overall management plan. The pace of progression throughout the course of any intervention should be mutually agreed.’

Specialist Referral

> We have produced a leaflet that explains how to obtain a specialist referral, provides up-to-date information on how to find an NHS  hospital specialist and what to expect, and also contains a section on paying to go private if this should prove necessary.

Part 6: 

Clinical History

With a diagnosis of ME/CFS being made largely on a patient’s clinical history, questions should address:

  • Previous medical and psychiatric illnesses. Most people with ME/CFS report normal levels of physical fitness and activity before being ill.
  • Previous operations and blood transfusions – query the possibility of hepatitis C infection if blood transfusion took place prior to September 1991.
  • Occupational history, including exposure to chemicals, solvents, pesticides and birds/animals – e.g. possibility of psittacosis.
  • Precipitating events involving specific infections – e.g. a tick bite and Lyme disease.
  • Reactions to vaccinations, toxins, trauma or surgery.
  • Presence of severe stress or athletic overtraining.
  • Drug use (prescribed, illegal – including cannabis) and alcohol history.
  • Travel – including reaction to vaccinations and contact with infections (e.g. dengue fever) while abroad.
  • Clinical features (e.g. weight loss, prominent myalgia or arthralgia, transient neurological events) which indicate that other possible diagnostic explanations need to be pursued.
  • Gynaecological history – query the possibility of early menopause. One study has indicated that endometriosis may be more common in women with ME/CFS (Sinaii et al 2002).
  • Social history – query the possibility of HIV or hepatitis B/C infection where appropriate. Acute HIV seroconversion may cause a glandular fever-like reaction with fever, malaise, lymphadenopathy and liver function abnormalities.
  • Family history – are there other family members with an ME/CFS-like illness?
  • Age – fatigue is quite common during adolescence where it may be related to social factors, including the use of recreational drugs and alcohol, as well as to erratic sleep patterns. Although ME/CFS does occur in later life, it is unusual for ME/CFS to develop over the age of 60. So very careful consideration should always be given to other explanations when making a new diagnosis of ME/CFS in older age groups – even though there may not be any symptoms, signs or blood test abnormalities that are suggestive of other explanations for increasing fatigue, such as a malignancy.
  • Establishing a clear picture of the effects of ME/CFS on a patient’s lifestyle is important when it comes to management and benefit entitlement.


  • Questions should therefore be asked about employment, education, family responsibilities and the degree of functional impairment that is occurring.


  • It can also be helpful to ask the person to describe what happens during a typical 24-hour period in their life.

Part 7: 

Differential Diagnosis

Chronic fatigue, whereby people experience ongoing problems with both physical and mental functioning, is a very common complaint in primary care. As a result, these people are unable to plan and take part in a wide range of normal everyday activities.

In those with idiopathic chronic fatigue, the fatigue is often relieved by reducing physical and mental activity and having a good night’s sleep, but this is not the case in people with ME/CFS.

There are many autoimmune, infective, metabolic and neurological conditions that often have debilitating fatigue as a key clinical feature – sometimes as a presenting feature.

Examples include:

  • Non-alcoholic fatty liver disease (Newton et al 2008),
  • Primary biliary cirrhosis (Newton et al 2006),
  • Scleroderma (Sandusky et al 2009),
  • Sjögren’s syndrome (Calabrese et al 1994),
  • Systemic lupus erythematosus, hepatitis C and multiple sclerosis (Berger et al 2013; Gaber et al 2014).

These conditions have been misdiagnosed as ME/CFS – so serious consideration should be given to excluding them, especially where the onset is gradual and there is no clear triggering infection.

Remember that ‘new’ symptoms should not be automatically ascribed to ME/CFS.

The importance of considering other possible diagnostic explanations is illustrated in this conclusion from a review of clinic attendance and diagnosis at a specialist ME/CFS referral centre in Newcastle (Newton et al 2010):

‘Of the 40% of patients subsequently found not to have CFS, the most common diagnosis was fatigue associated with a chronic disease (47% of all alternative diagnoses); 20% had primary sleep disorders, 15% psychological/psychiatric illnesses and 4% a cardiovascular disorder. Thirteen per cent remained unexplained (5.2% of the total referrals).’

Although extensive and elaborate investigations are seldom needed, other causes of ME/CFS symptoms must be seriously considered where the history is atypical or where there are other symptoms and/or signs present that are not consistent with a diagnosis of ME/CFS.

Part 8: 

Recently Diagnosed

> If you have recently been diagnosed with ME/CFS, then you might like to read our leaflet that explains how to manage your illness and gives simple advice about a technique called pacing.

There’s an introduction to benefits, guidance about your emotions, how to explain things to other people and where to go to get some help.

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Visit our other pages in this section:

> What is ME?
> Symptoms, testing, and assessment
> Management
> Prognosis and quality of life
> Children and adolescents, NICE guideline on ME/CFS 

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