Tiredness & Fatigue in Adults

🔍 When to Suspect

Persistent tiredness not relieved by rest, impacting daily function, present for several weeks without a clear lifestyle cause

From the full topic in The Ocean Library: Tiredness & Fatigue in Adults

🧭 When to suspect

Tiredness or fatigue is one of the highest-volume presentations in primary care – a persistent, subjective lack of energy that is not relieved by rest and that interferes with work, social or daily functioning. It is a non-specific symptom with a very wide differential, ranging from everyday lifestyle and psychological causes through to serious organic disease.

The core clinical skill is twofold: read the pattern of the fatigue to direct the work-up, and never miss a red flag. Separating sleepiness (a tendency to doze off), physical fatigue (“no energy”) and mental fatigue (“can’t be bothered”) early on is the single most useful triage step, because each points to a different group of causes and a different management route.

Pattern of fatigue	Typical pointers	Think about
Sleepiness / hypersomnolence	Dozing off in the day, unrefreshing sleep, snoring, witnessed apnoeas	Obstructive sleep apnoea, poor sleep hygiene, shift work, sedating drugs
Physical / “no energy”	Breathlessness, exertional limitation, pallor, weight change, cold intolerance	Anaemia, hypothyroidism, diabetes, cardiac / respiratory / renal / hepatic disease, malignancy
Mental / “can’t be bothered”	Low mood, anhedonia, poor concentration, anxiety, identifiable life stress	Depression, anxiety, burnout, psychosocial stress
Activity-triggered (PEM)	Disproportionate, often delayed “crash” after minimal exertion, prolonged recovery	ME/CFS, frequently post-viral

Investigate unexplained fatigue that has persisted beyond around a month and cannot be attributed to an obvious recent cause – an acute illness, a period of sleep loss, an identifiable stressor or a culprit medication. Raise the index of suspicion for serious organic disease where there is unintentional weight loss, fever or night sweats, focal symptoms, or abnormal examination findings.

Source: NICE · NICE NG12

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