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.

Vomiting - dehydration; Diarrhea - dehydration; Diabetes - dehydration; Stomach flu - dehydration; Gastroenteritis - dehydration; Excessive sweating - dehydration

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

Older adults and people with certain diseases, such as diabetes, are also at higher risk for dehydration.

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

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.

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.

Dehydration caused by a stomach virus should get better on its own after a few days.

If you notice signs of dehydration and treat it quickly, you should recover completely.

Untreated severe dehydration may cause:

• Death
• Permanent brain damage
• Seizures

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.

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.

Published Date: August 10, 2021
Published By: Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, 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, McCormick T. Infectious diarrheal disease and dehydration. In: Walls RM, Hockberger RS, Gausche-Hill M, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 9th ed. Philadelphia, PA: Elsevier; 2018:chap 172.