Chronic Fatigue Syndrome (CFS)

Diagnostic Criteria

• Fatigue: Persistent, unexplained fatigue >6 months, not relieved by rest, causing significant functional impairment.

• Associated Symptoms (≥4, lasting >6 months):

  • Impaired memory or concentration

  • Post-exertional malaise

  • Unrefreshing sleep

  • Muscle or multi-joint pain (without swelling/redness)

  • New or severe headaches

  • Sore throat or tender cervical/axillary lymph nodes

Symptoms and Key Features

• Hallmark Symptoms: Post-exertional malaise, unrefreshing sleep, cognitive impairment

• Common Features: Orthostatic intolerance, often acute onset (post-viral), crimson crescents in the oropharynx

Triggers

• Post-viral fatigue (e.g. Epstein-Barr virus)

• Psychological or physical stress

• Immune dysregulation (potential role)

• Vitamin D deficiency

Differentials

• Obstructive sleep apnoea

• Thyroid dysfunction (hypothyroidism/hyperthyroidism)

• Anaemia or iron deficiency

• Fibromyalgia

• Depression or generalised anxiety disorder

• Multiple sclerosis

• HIV, hepatitis

Investigations

• Initial Screening:

  • FBC

  • ESR/CRP

  • UEC, LFT, TFT

  • Vitamin D (exclude deficiency)

• Further Testing (if indicated):

  • Coeliac serology (malabsorption)

  • Cortisol (adrenal insufficiency)

  • Infectious workup (e.g. EBV serology)

Management

• Non-Pharmacological:

  • Graded Exercise Therapy (low-level activity with planned rest periods)

  • CBT for coexisting depression/anxiety

  • Pacing to avoid over-exertion and manage post-exertional malaise

  • Sleep hygiene to address unrefreshing sleep

• Pharmacological:

  • Pain relief (NSAIDs or paracetamol)

  • Sedatives or low-dose antidepressants (e.g. amitriptyline) for sleep issues

  • Avoid polypharmacy; limited evidence for specific medications