Medical Matters > Idiopathic Chronic Fatigue

ME Essential Summer 2019


What is the difference between chronic fatigue and ME/CFS? A friend of mine has been told by her doctor that she has something called idiopathic chronic fatigue. But I know that she has very similar symptoms to ME/CFS.


‘Idiopathic' is medical jargon for something being unexplained. Idiopathic chronic fatigue (ICF) is a diagnostic label that is used by some doctors for people who have persisting fatigue as the main – but often not the only – symptom. It should only be given when no underlying medical or mental health condition can be found that might be causing symptoms.

Before a diagnosis of ICF is made, patients should receive a proper clinical assessment (by taking a careful clinical history, having a full physical examination and checking blood test results) to see if there is a medical reason (e.g., hypothyroidism, anaemia, or ME/CFS) or mental health reason (e.g., depression) that can explain their symptoms. A patient should be properly assessed to see if they meet diagnostic criteria for ME/CFS in accordance with the recommendations in the 2021 NICE Clinical Guideline (below).

It is important to check all possible reasons for this symptom occurring especially if it develops suddenly. If it is determined a patient does not have a medical or mental health condition that explains the chronic fatigue, then a diagnosis of ICF might be made. But my own view is that ICF is being used by some doctors as a ‘dustbin diagnosis’ – rather like ‘tired all the time’ – and that it can be given inappropriately because proper assessments have not been completed.

Labelling someone as having ICF can result in serious medical conditions, such as cancer, being missed. The term is unhelpful when it comes to management – as many doctors give up on these patients and say that ’nothing can be done’. This can result in a patient going away to try and cope as best they can without any further medical help or follow-up and being less inclined to return to their GP if new symptoms occur or existing symptoms worsen. It is also worth noting that ICF is not recognised in the International Classification of Diseases (WHO ICD-11) or by SNOMED-CT – the electronic diagnostic coding system used by the NHS. Patients should question their doctor if they receive a diagnosis of ICF or ‘chronic fatigue', and ask for a second opinion from another doctor or ME/CFS Specialist Service if they are not happy with it.

More information

  • The ME Association has produced a free summary of the 2021 NICE Clinical Guideline for ME/CFS. The Guideline includes information about symptom recognition, diagnosis, and management. We suggest that you familarise yourself with the recommendations and discuss those that are most relevant with your GP, ME/CFS Specialist Service, or Social Care service (as appropriate).


Medical Matters is for information purposes only. The answers provided by Dr Shepherd and the ME Association’s other expert advisers should not be construed as medical advice. We recommend that any information you deem relevant is discussed with your GP as soon as possible. It is important to obtain advice from a GP who is in charge of your clinical care, who knows you well, and who can consider other likely causes for symptoms. Seek personalised medical advice whenever a new symptom arises, or an existing symptom worsens. Don't assume that new or worsened symptoms are a result of having ME/CFS.

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