What are the causes of experiencing fatigue, hot flashes, and chills?

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Last updated: May 24, 2025 • View editorial policy

Differential Diagnosis for Feeling Tired, Hot, and Cold

Single Most Likely Diagnosis

  • Viral Infection: This is often the most common cause of feeling tired, hot, and cold, as many viral infections, such as the flu or common cold, present with these symptoms due to the body's immune response.

Other Likely Diagnoses

  • Anxiety or Stress: Prolonged periods of anxiety or stress can lead to feelings of fatigue, and the body's "fight or flight" response can cause fluctuations in temperature perception, making one feel hot and cold.
  • Hypothyroidism: An underactive thyroid gland can cause fatigue, and some people may experience temperature intolerance, feeling hot or cold more easily than others.
  • Anemia: A lack of red blood cells or hemoglobin can lead to fatigue, and some individuals may feel cold due to decreased blood flow and oxygen delivery to tissues.
  • Diabetes: Uncontrolled diabetes can cause fatigue, and fluctuations in blood sugar levels may lead to feelings of hot and cold due to changes in blood flow and sweating.

Do Not Miss Diagnoses

  • Sepsis: Although less likely, sepsis is a life-threatening condition that can present with fever (hot), chills (cold), and fatigue. Early recognition and treatment are crucial.
  • Meningitis: This infection of the membranes surrounding the brain and spinal cord can cause fever, chills, and fatigue, among other symptoms. Prompt diagnosis and treatment are essential to prevent serious complications.
  • Thyroid Storm: A rare but life-threatening complication of untreated or undertreated hyperthyroidism, characterized by extreme fatigue, heat intolerance, and other symptoms.
  • Adrenal Insufficiency: A condition where the adrenal glands do not produce enough hormones, leading to fatigue, temperature intolerance, and other symptoms. If left untreated, it can be life-threatening.

Rare Diagnoses

  • Mitochondrial Myopathies: A group of rare genetic disorders affecting the mitochondria, leading to fatigue, temperature intolerance, and other symptoms.
  • Ehlers-Danlos Syndrome: A rare genetic disorder affecting connective tissue, which can cause fatigue, temperature regulation issues, and other symptoms.
  • Autonomic Dysfunction: A rare condition affecting the autonomic nervous system, leading to temperature regulation problems, fatigue, and other symptoms.
  • Neurodegenerative Diseases: Certain rare neurodegenerative diseases, such as multiple system atrophy, can cause fatigue, temperature intolerance, and other symptoms.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.