lethargic

Lethargic describes a state of reduced energy, alertness, and responsiveness. A lethargic person often appears drowsy, slow to speak or move, and slow to respond to questions. In medical contexts, lethargy refers to a lowered level of arousal that is greater than ordinary tiredness but not as severe as stupor or coma. It is a symptom rather than a disease, and it can accompany many different conditions.

Common signs and symptoms include slow speech, reduced attention and concentration, delayed reactions, decreased spontaneous movement, and difficulty waking or staying awake. People may also show a lack of interest or motivation, and report feeling weak or mentally foggy. Distinguishing lethargy from fatigue or sleepiness can be challenging, as these terms overlap in daily speech but have distinct clinical implications.

Causes are diverse and can be organized into medical, medication-related, and psychosocial categories. Medical causes include thyroid disorders, infections, liver or kidney failure, metabolic disturbances (such as electrolyte imbalances or hypoglycemia), anemia, malnutrition, and dehydration. CNS disorders (stroke, brain injury, tumors, encephalitis) and neurological conditions may produce lethargy. Medications and substances, including sedatives, opioids, antihistamines, alcohol, and anticholinergics, can cause lethargy. Psychiatric conditions such as major depression or severe anxiety can also present with lethargic symptoms, as can sleep disorders and excessive fatigue from chronic illness.

Evaluation typically includes a thorough history and physical examination, vital signs, and targeted laboratory tests (glucose, complete blood count, metabolic panel, liver and kidney function, thyroid tests). Additional investigations (imaging, infection tests, vitamin levels) are guided by findings.

Management aims to treat the underlying cause, ensure safety, and support hydration, nutrition, and sleep. In urgent cases, prompt medical attention is essential to identify reversible conditions and prevent deterioration. Prognosis depends on the underlying issue and response to treatment.