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Last updated: December 7, 2020

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Dehydration (exsiccosis) is a state of decreased total body water. This decrease in total body water occurs in excess of sodium (also called “free water loss”), resulting in a hypertonic and hypernatremic state. The terms “hypotonic” and “isotonic” are sometimes incorrectly used to describe dehydration, but these terms are only associated with hypovolemia and hypovolemic shock. Dehydration most often affects children and the elderly. Treatment of dehydration involves correcting the free water deficit.


Clinical feature Mild dehydration Moderate dehydration Severe dehydration
Decrease in body weight < 3% 3–9%

> 9%

Symptoms Mental status Alert Restless, irritable Lethargic, confused
Thirst Slightly increased Thirsty; drinks eagerly Refuses to drink
Urine output Normal ↓ (dark concentrated urine) ↓↓
Signs specific to dehydration Eyes Normal Slightly sunken Significantly sunken
Tears (especially children) Normal Decreased Absent
Tongue Moist Dry Parched
Skin turgor Instant recoil Recoil within 2 seconds Recoil after 2 seconds; significant skin tenting
In infants: anterior fontanelle Normal Slightly sunken Significantly sunken
Signs of hypovolemia and hypovolemic shock Pulse rate Normal Mildly tachycardic Initially tachycardia → later bradycardia
Blood pressure Normal Normal; postural hypotension may be present Hypotension
Capillary refill time Normal (< 2 seconds) 2–3 seconds > 3 seconds
Extremities Warm Cool Mottled
Breathing Normal Tachypnea Tachypnea with deep breathing (Kussmaul breathing)



Patients who are hypovolemic as a result of severe dehydration require immediate fluid resuscitation with crystalloid solutions.

  1. Fluid resuscitation
    • Severe hypovolemia
      • Children: rapid infusion of 20 mL/kg of isotonic saline → reassess → repeat as needed
      • Adults: rapid infusion of isotonic crystalloid → reassess → repeat as needed
    • Moderate hypovolemia
      • Children: consider oral hydration therapy or 10 mL/kg of isotonic saline → reassess → repeat as needed
  2. Correction of electrolyte abnormalities



We list the most important complications. The selection is not exhaustive.

  1. Faes MC, Spigt MG, Olde Rikkert MGM. Dehydration in geriatrics. Geriatrics & Aging. 2007; 10 (9): p.590-596.
  2. Wook Lee J. Fluid and electrolyte disturbances in critically ill patients. Electrolyte Blood Press. 2010; 8 (2): p.72-81. doi: 10.5049/EBP.2010.8.2.72 . | Open in Read by QxMD
  3. Huang LJ. Dehydration. In: Corden TE, Dehydration. New York, NY: WebMD. http://emedicine.medscape.com/article/906999. Updated: November 27, 2016. Accessed: April 12, 2017.
  4. Sterns RH. Etiology, Clinical Manifestations, and Diagnosis of Volume Depletion in Adults. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/etiology-clinical-manifestations-and-diagnosis-of-volume-depletion-in-adults.Last updated: February 29, 2016. Accessed: April 12, 2017.
  5. Fleisher GR, Ludwig S. Textbook of Pediatric Emergency Medicine . Lippincott Williams & Wilkins ; 2010
  6. Somers MJ. Clinical Assessment and Diagnosis of Hypovolemia (Dehydration) in Children. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/clinical-assessment-and-diagnosis-of-hypovolemia-dehydration-in-children.Last updated: November 30, 2016. Accessed: April 12, 2017.
  7. Sterns RH. General Principles of Disorders of Water Balance (Hyponatremia and Hypernatremia) and Sodium Balance (Hypovolemia and Edema). In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/general-principles-of-disorders-of-water-balance-hyponatremia-and-hypernatremia-and-sodium-balance-hypovolemia-and-edema.Last updated: February 1, 2017. Accessed: April 12, 2017.
  8. Davenport M, Syed SHS. Handbook of Pediatric Surgery . Springer Verlag London Limited ; 2010
  9. Dasgupta A, Wahed A. Clinical Chemistry, Immunology and Laboratory Quality Control. Academic Press ; 2013
  10. Horowitz GL. Creatinine. In: Staros EB, Creatinine. New York, NY: WebMD. http://emedicine.medscape.com/article/2054342. Updated: December 10, 2014. Accessed: April 12, 2017.
  11. Lukitsch I. Hypernatremia. In: Batuman V, Hypernatremia. New York, NY: WebMD. http://emedicine.medscape.com/article/241094. Updated: August 24, 2016. Accessed: April 14, 2017.
  12. Chiasson J, Aris-Jilwan N, Bélanger R et al. Diagnosis and treatment of diabetic ketoacidosis and the hyperglycemic hyperosmolar state. CMAJ. 2003; 168 (7): p.859–866.
  13. Somers M. Treatment of Hypovolemia (Dehydration) in Children. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/treatment-of-hypovolemia-dehydration-in-children.Last updated: November 13, 2016. Accessed: January 19, 2018.
  14. Mandel J, Palevsky PM. Treatment of Severe Hypovolemia or Hypovolemic Shock in Adults. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/treatment-of-severe-hypovolemia-or-hypovolemic-shock-in-adults.Last updated: January 17, 2018. Accessed: January 19, 2018.
  15. Faubel, S and Topf, J. The Fluid, Electrolyte and Acid-Base Companion. Alert and Oriented Publishing Co ; 1999
  16. Sterns RH. Manifestations of Hyponatremia and Hypernatremia in Adults. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/manifestations-of-hyponatremia-and-hypernatremia-in-adults.Last updated: January 5, 2016. Accessed: February 14, 2017.
  17. Kolecki P. Hypovolemic Shock. In: Brenner BE, Hypovolemic Shock. New York, NY: WebMD. http://emedicine.medscape.com/article/760145. Updated: October 13, 2016. Accessed: April 14, 2017.
  18. Richards MJ, Stuart RL. Causes of Infection in Long-Term Care Facilities: An Overview. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/causes-of-infection-in-long-term-care-facilities-an-overview.Last updated: November 3, 2015. Accessed: April 14, 2017.
  19. Touhy TA, Jett KF. Ebersole and Hess' Gerontological Nursing & Healthy Aging . Elsevier Health Sciences ; 2016
  20. UpToDate. Physical findings of volume depletion in infants and children. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/image?imageKey=PEDS%2F76198&topicKey=PEDS%2F6142&rank=1~150&source=see_link&search=dehydration%20children.Last updated: January 1, 2017. Accessed: April 12, 2017.