Dehydration
Dehydration occurs when your body does not have as much water and fluids as it needs.
Dehydration can be mild, moderate, or severe, based on how much of your body's fluid is lost or not replaced. Severe dehydration is a life-threatening emergency.
Causes
You can become dehydrated if you lose too much fluid, do not drink enough water or fluids, or both.
Your body may lose a lot of fluid from:
- Sweating too much, for example, from exercising in hot weather
- Fever
- Vomiting or diarrhea
- Urinating too much (uncontrolled diabetes or some medicines, like diuretics, can cause you to urinate a lot)
You might not drink enough fluids because:
- You do not feel like eating or drinking because you are sick
- You are nauseated
- You have a sore throat or mouth sores
Sore throat
Pharyngitis, or sore throat, is discomfort, pain, or scratchiness in the throat. It often makes it painful to swallow.
Read Article Now Book Mark ArticleMouth sores
Trench mouth is an infection that causes swelling (inflammation) and ulcers in the gums (gingivae). The term trench mouth comes from World War I, wh...
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Older adults and people with certain diseases, such as diabetes, are also at higher risk for dehydration.
Symptoms
Signs of mild to moderate dehydration include:
- Thirst
- Dry or sticky mouth
- Not urinating much
- Darker yellow urine
- Dry, cool skin
- Headache
- Muscle cramps
Signs of severe dehydration include:
- Not urinating, or very dark yellow or amber-colored urine
- Dry, shriveled skin
- Irritability or confusion
- Dizziness or lightheadedness
- Rapid heartbeat
- Rapid breathing
- Sunken eyes
- Listlessness
- Shock (not enough blood flow through the body)
- Unconsciousness or delirium
Exams and Tests
Your health care provider will look for these signs of dehydration:
- Low blood pressure.
Low blood pressure
Low blood pressure occurs when blood pressure is much lower than normal. This means the heart, brain, and other parts of the body may not get enough...
Read Article Now Book Mark Article - Blood pressure that drops when you stand up after lying down.
- White finger tips that do not return to a pink color after your provider presses the fingertip.
After your provider presses the fingert...
The capillary nail refill test is a quick test done on the nail beds. It is used to monitor dehydration and the amount of blood flow to tissue....
Read Article Now Book Mark Article - Skin that is not as elastic as normal. When the provider pinches it into a fold, it may slowly sag back into place. Normally, skin springs back right away.
Skin that is not as elastic as normal
Skin turgor is the skin's elasticity. It is the ability of skin to change shape and then return to normal.
Read Article Now Book Mark Article - Rapid heart rate.
Rapid heart rate
A bounding pulse is a strong throbbing felt over one of the arteries in the body. It is due to a forceful heartbeat.
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Your provider may do lab tests such as:
- Blood tests to check kidney function
Kidney function
The creatinine blood test measures the level of creatinine in the blood. This test is done to see how well your kidneys are working. Creatinine in t...
Read Article Now Book Mark Article - Urine tests to see what may be causing dehydration
Urine tests
Urine specific gravity is a laboratory test that shows the total concentration of all chemical particles in the urine.
Read Article Now Book Mark Article - Other tests to see what may be causing dehydration (blood sugar test for diabetes)
Blood sugar test for diabetes
Diabetes is a long-term (chronic) disease in which the body cannot regulate the amount of sugar in the blood.
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Treatment
To treat dehydration:
- Try sipping water or sucking on ice cubes.
- Try drinking water or sports drinks that contain electrolytes.
- Do not take salt tablets. They can cause serious complications.
- Ask your provider what you should eat if you have diarrhea.
What you should eat if you have diarrhe
Diarrhea is the passage of loose or watery stool. For some, diarrhea is mild and will go away within a few days. For others, it may last longer. I...
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For more severe dehydration or heat emergency, you may need to stay in a hospital and receive fluid through a vein (IV). The provider will also treat the cause of the dehydration.
Heat emergency
Heat emergencies or illnesses are caused by exposure to extreme heat or sun. Heat illnesses can be prevented by being careful in hot, humid weather....
Read Article Now Book Mark ArticleDehydration caused by a stomach or intestinal virus should get better on its own after a few days.
Stomach or intestinal virus
Viral gastroenteritis is an infection of the stomach and intestine caused by a virus. The infection can lead to diarrhea and vomiting. It is someti...
Read Article Now Book Mark ArticleOutlook (Prognosis)
If you notice signs of dehydration and treat it quickly, you should recover completely.
Possible Complications
Untreated severe dehydration may cause:
- Death
- Permanent brain damage
- Seizures
Seizures
A seizure is the physical changes in behavior that occurs during an episode of specific types of abnormal electrical activity in the brain. The term ...
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When to Contact a Medical Professional
You should call 911 or the local emergency number if:
- The person loses consciousness at any time.
- There is any other change in the person's alertness (for example, confusion or seizures).
- The person has a fever over 102°F (38.8°C).
- You notice symptoms of heatstroke (such as rapid pulse or rapid breathing).
- The person's condition does not improve or gets worse despite treatment.
Prevention
To prevent dehydration:
- Drink plenty of fluids every day, even when you are well. Drink more when the weather is hot or you are exercising.
- If anyone in your family is ill, pay attention to how much they are able to drink. Pay close attention to children and older adults.
- Anyone with a fever, vomiting, or diarrhea should drink plenty of fluids. DO NOT wait for signs of dehydration.
- If you think you or someone in your family may become dehydrated, call your provider. Do this before the person becomes dehydrated.
Reviewed By
Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
Kenefick RW, Cheuvront SN, Leon LR, O'Brien KK. Dehydration and rehydration. In: Auerbach PS, Cushing TA, Harris NS, eds. Auerbach's Wilderness Medicine. 7th ed. Philadelphia, PA: Elsevier; 2017:chap 89.
Padlipsky P, White W. Pediatric infectious diarrheal disease and dehydration. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 167.