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Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

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A definitive diagnosis of fatigue is difficult to make. The objective is to identify any underlying physical, psychosocial or physiological factors which may be the source of tiredness.

  • medications and toxic exposures
    • long-acting antihistamines, corticosteroids, neuroleptics, antiarrhythmics (e.g., amiodarone), antidepressants and antihypertensives (e.g., clonidine, alpha methyldopa and beta-blockers) and some herbal remedies
    • environmental toxins - carbon monoxide, lead, mercury and arsenic (1)

  • history
    • fatigue's duration (recent, prolonged or chronic), onset (sudden or progressive), recovery period (short or long)
    • patients physical activity (sedentary or active) (1)
    • aggravating and relieving factors (2)
    • particular useful in differentiating chronic fatigue from chronic fatigue syndrome (CFS) - CFS presents with sudden onset with recovery occurring in hours or days
    • psychiatric assessment
      • fatigue is the chief complaint in most of the psychiatric disorders (3)
      • should enquire about depression, stress, anxiety, eating disorders, somatisation disorder (2,3)
      • substance abuse (caffeine, alcohol and illicit drugs)
    • assessment for sleep disorder
      • sleep apnoea, excessive sleepiness and parasomnias (1)

  • physical examination
    • to identify any organ based diseases e.g - breathlessness, weight loss, anorexia (2)

The following can be used as first line investigations in primary care to rule out any serious and common underlying diseases:

  • FBC
  • ESR
  • thyroid stimulating hormone
  • fasting blood glucose level
  • additional possible investigations include:
    • liver function test
    • serum urea, electrolyte and creatinine levels
    • serum ferritin (indicated as an initial investigation in children and young adults only)
    • urinalysis for protein, blood and glucose
    • blood test for gluten sensitivity
    • serum calcium (1,2)


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