**R53 — Malaise and fatigue** captures generalized weakness and tiredness without a specific cause identified. Sub-codes: R53.0 (neoplasm-related fatigue), R53.1 (asthenia/weakness), R53.81 (other malaise), R53.83 (other fatigue).
This is one of the most common and least specific presenting symptoms in clinical medicine — workup typically focuses on sleep, mood, anemia, thyroid, and chronic disease.
Belongs to **Chapter R** — Symptoms, signs.
