CFS - Diagnosing chronic fatigue syndrome

There is no test for chronic fatigue syndrome (CFS), but there are clear guidelines to help doctors diagnose it.

It can take a long time for the condition to be diagnosed, as other conditions that cause similar symptoms need to be ruled out first. Therefore, you may be given some advice about managing your symptoms before a diagnosis is confirmed (see treating CFS for more information).

If you see your GP about persistent and excessive fatigue, they will ask you about your medical history and may carry out a physical examination.

You may have blood tests, urine tests and scans to rule out other conditions, such as anaemia (lack of red blood cells), an underactive thyroid gland or liver and kidney problems.

NICE guidelines for diagnosing CFS

Guidelines released in 2007 from the National Institute for Health and Care Excellence (NICE) state that doctors should consider diagnosing CFS if a person has fatigue and all of the following apply:

• it is new or had a clear starting point (it has not been a lifelong problem)
• it is persistent and/or recurrent
• it is unexplained by other conditions
• it substantially reduces the amount of activity someone can do
• it feels worse after physical activity

The person should also have one or more of these symptoms:

• difficulty sleeping, or insomnia
• muscle or joint pain without inflammation 
• headaches 
• painful lymph nodes that are not enlarged
• sore throat 
• poor mental function, such as difficulty thinking
• symptoms getting worse after physical or mental exertion
• feeling unwell or having flu-like symptoms
• dizziness or nausea
• heart palpitations, without heart disease

This diagnosis should be confirmed by a clinician after other conditions have been ruled out, and the above symptoms have persisted for at least four months in an adult and three months in a child or young person.

For more information, read the NICE guidelines on CFS.