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Causes
By Mayo Clinic staff
Water is essential to human life: It forms the basis for all body fluids, including blood and digestive juices; it aids in the transportation and absorption of nutrients; and it helps eliminate waste.
If you're an average adult, every day you lose more than 10 cups (close to 2.5 liters) of water simply by sweating, breathing and eliminating waste. You also lose electrolytes — minerals such as sodium, potassium and calcium that maintain the balance of fluids in your body. Normally, you can replenish what you've lost through the foods and liquids you consume, even when you're active.
But when you eliminate more water and salts than you replace, dehydration results — your system literally dries out. Sometimes dehydration occurs for simple reasons: You don't drink enough because you're sick or busy, or because you lack access to potable water when you're traveling, hiking or camping.
Other dehydration causes include:
- Diarrhea, vomiting. Severe, acute diarrhea — that is, diarrhea that comes on suddenly and violently — can cause a tremendous loss of water and electrolytes in a short amount of time. If you have vomiting along with diarrhea, you lose even more fluids and minerals. Children and infants are especially at risk. Dehydration is a leading cause of death in children worldwide. In the United States, up to 300 children die of dehydration each year.
- Fever. In general, the higher your fever, the more dehydrated you may become. If you have a fever in addition to diarrhea and vomiting, you lose even more fluids.
- Excessive sweating. You lose water when you sweat. If you engage in vigorous activity and don't replace fluids as you go along, you can become dehydrated. Hot, humid weather increases the amount you sweat and the amount of fluid you lose. But you can also become dehydrated in winter if you don't replace lost fluids. Preteens and teens who participate in sports may be especially susceptible, both because of their body weight, which is generally lower than that of adults, and because they may not be experienced enough to know the warning signs of dehydration.
- Increased urination. This is most often the result of undiagnosed or uncontrolled diabetes mellitus, a disease that affects the way your body uses blood sugar and that often causes increased thirst and more frequent urination. Another type of diabetes, diabetes insipidus, also is characterized by excessive thirst and urination, but in this case the cause is a hormonal disorder that makes your kidneys unable to conserve water. Certain medications — diuretics, antihistamines, blood pressure medications and some psychiatric drugs — as well as alcohol also can lead to dehydration, generally because they cause you to urinate or perspire more than normal.
- Burns. Doctors classify burns according to the depth of the injury and the extent of tissue damage. Third-degree burns are the most severe, penetrating all three layers of skin, and often destroying sweat glands, hair follicles and nerve endings. People with third-degree burns or extensive first- or second-degree burns experience profound fluid loss, and the resulting dehydration can be life-threatening.
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- Preventing dehydration from diarrhea. Journal of the American Medical Association. 2001;285(3):362.
- Wellbery C. Diagnosing dehydration in children. American Family Physician. 2005;71(5).
