Symptom Severity & Impact

The International Consensus Primer (ICP) for Myalgic Encephalomyelitis (ME) (2012) has four categories of severity:

Mild: meet criteria and have a significant reduction in activity level;

Moderate: approximately 50% reduction in pre-illness activity level;

Severe: mostly housebound;

Very severe: mostly bedbound and require assistance with daily functions. Those who are very severely affected are too ill to attend regular medical appointments.

The UK National Institute for Health and Clinical Excellence (NICE) guideline on ME/CFS (and here) outlines three levels of severity – mild, moderate and severe, are more detailed than the ICP – and are as follows:


  • “People with mild CFS/M.E. are mobile, can care for themselves and can do light domestic tasks with difficulty. Most are still working or in education, but to do this they have probably stopped all leisure and social pursuits. They often take days off, or use the weekend to cope with the rest of the week.”


  • “People with moderate CFS/M.E. 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, school or college and need rest periods, often sleeping in the afternoon for 1 or 2 hours. Their sleep at night is generally poor quality and disturbed.”


  • “People with severe CFS/M.E. are unable to do any activity for themselves, or can carry out minimal daily tasks only (such as face washing, cleaning teeth). They have severe cognitive difficulties and 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 noise.”

The NICE acknowledges that the physical symptoms of ME/CFS can be as disabling as multiple sclerosis, rheumatoid arthritis and congestive heart failure.


What is ME/CFS?


What causes ME/CFS?

Who gets ME/CFS?

Further reading


Some Relevant Journal Articles

Hardcastle, S. L., et al. “Severity Scales for Use in Primary Health Care to Assess Chronic Fatigue Syndrome/Myalgic Encephalomyelitis.Health Care Women Int, 2014, 0: 1-16.

Hardcastle, S. L., et al. “Analysis of the relationship between immune dysfunction and symptom severity in patients with Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME).J. Clin. Cell. Immunol., 2014, 5(1): 1000190/1000191-1000190/1000199.

Baraniuk, J. N., et al. “A Chronic Fatigue Syndrome (CFS) severity score based on case designation criteria.Am J Transl Res, 2013, 5(1): 53-68.

Jones, D. E. J., et al. “Fatigue severity remains stable over time and independently associated with orthostatic symptoms in chronic fatigue syndrome: a longitudinal study.J Intern Med, 2011, 269(2): 182-188.

White, A. T., et al. “Severity of symptom flare after moderate exercise is linked to cytokine activity in chronic fatigue syndrome.Psychophysiology, 2010, 47(4): 615-624.

Hurwitz, B. E., et al. “Chronic fatigue syndrome: illness severity, sedentary lifestyle, blood volume and evidence of diminished cardiac function.Clin Sci (Lond), 2010, 118(2): 125-135.

Fletcher, M. A., et al. “Plasma neuropeptide Y: a biomarker for symptom severity in chronic fatigue syndrome.Behav. Brain Funct., 2010, 6: 76.

Nijs, J., et al. “Can pacing self-management alter physical behavior and symptom severity in chronic fatigue syndrome? A case series.J Rehabil Res Dev, 2009, 46(7): 985-996.

Jason, L., et al. “The impact of energy modulation on physical functioning and fatigue severity among patients with ME/CFS.Patient Educ Couns, 2009, 77(2): 237-241.