Chronic Fatigue & Weakness
Medically Reviewed & Fact-CheckedBy MD, Emergency Medicine & Internal Medicine
Reviewed: 9/6/2026Overview
Fatigue is a pervasive sense of tiredness, lack of energy, and physical or mental exhaustion that is not relieved by sleep or rest, distinctly different from simple somnolence.
Possible Causes
- Iron deficiency anemia and nutritional deficiencies (Vitamin B12, D)
- Endocrine: Hypothyroidism, Diabetes Mellitus, Adrenal Insufficiency
- Chronic sleep apnea and sleep disorders
- Chronic kidney disease or congestive heart failure
- Post-viral fatigue syndrome and Long COVID
- Major Depressive Disorder
When to Seek Care
Consult your healthcare provider for laboratory workup (CBC, ferritin, TSH, HbA1c, metabolic panel) if fatigue interferes with daily functioning or persists past 4 weeks.
The information provided on this website is for educational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider with any questions you may have regarding a medical condition.