How to Diagnose ME/CFS (Canadian Consensus Criteria)

Canadian Consensus Criteria (CCC), 2003

Term used: ME/CFS

Post Exertional Malaise (PEM) is a mandatory symptom for diagnosis.


  • Fatigue
  • Post-exertional malaise (PEM)
  • Sleep dysfunction
  • Cognitive difficulties/ impairment
  • Chronic pain

At least 1 symptom from 2 of the following*

  • Autonomic manifestations*
  • Neuroendocrine manifestations*
  • Immune manifestations*

* Each of these categories has a list of symptoms which would qualify as meeting the criteria. You can read the full list here:

This is the most widely used diagnostic criteria amongst doctors who have expertise in ME/CFS. It is also the diagnostic criteria most commonly used in research (NIH recommended it be used by its Collaborative Research Centers) although it was designed for clinical use.

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