Medical Specialties: Emergency medicine, Family practice, Internal medicine

Clinical Definition

Dehydration is a lack of adequate water in the body that can be hazardous and even life-threatening, often occurring due to inadequate fluid intake during hot weather, exercise, fever, diarrhea or vomiting. Older adults and those on diuretic medications for hypertension are also prone to dehydration.  Symptoms may include dry mouth, dry cough, dizziness and little to no urine output. Treatment involves fluid replacement, using water, electrolyte solutions, freezer pops or intravenous fluids.

In Our Own Words

Dehydration, or a lack of enough water in the body, can range from mild to severe, depending on how much fluid has been lost or not replaced. When severe, the condition can be even life-threatening. Dehydration can occur during hot weather and vigorous exercise; it also can occur if fever, vomiting and diarrhea symptoms are present. Taking diuretic medication (i.e., ''water pills") for high blood pressure (i.e., hypertension) is another possible cause of dehydration. The condition is more common with advancing age and can be especially dangerous in the elderly and in infants and children.


Symptoms may include little to no urine output, lethargy, dry mouth and dizziness. Infants may have sunken fontanels (i.e., the soft spots on the head) because of low fluid volume inside. Treatment is fluid replacement – either with water, electrolyte solutions, freezer pops or, for severe forms, intravenous fluids administered by health care providers. Untreated, dehydration can lead to permanent damage to the brain, seizures or death. 

Relevant Conditions
Side Effects
  • Fatigue and thirst
  • Loss of appetite
  • Dry, sticky mouth
  • Low or no urine output
  • Dark yellow urine
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  • Cleveland Clinic. "Dehydration (Adults)." Accessed August 2013.
  • University of Maryland Medical Center. "Dehydration." Updated May 2013. Accessed August 2013.
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