Could you go for some H2O?
You're thirsty. What do you do? Reach for something to drink. Thirst is your body's handy way of signaling that you need to replenish your stores of water. Because drinking more is the best way to prevent or combat dehydration, thirst actually serves the practical purpose of making sure your body has enough water to perform its functions.
Most of us have been mildly dehydrated at some point in our lives; usually, we can replace our lost fluids by drinking more. In some cases, though, mild dehydration becomes severe.
Preventing excess water loss is the best way to make sure that you don't become severely dehydrated. You can treat yourself if you recognize warning signs; they'll also help you know if you need to seek medical attention. While dehydration can be hard on your body if it goes too far, if identified and treated early enough, complete recovery is very likely.
In a healthy individual, water accounts for two-thirds of body weight. The average adult needs to consume at least 32 ounces of liquid (four 8-ounce glasses) each day just to maintain basic functions -- an active adult will need to consume at least two or three times that much. About 10% of water in the body is in the bloodstream and must be kept at a fairly consistent level to keep the body working properly. Our bodies need salts called electrolytes, such as sodium, potassium, magnesium, and calcium, in order for energy conversion to take place at a cellular level. Electrolytes are depleted along with loss of water. As a result, dehydration disrupts the body's normal functions.
Initially, dehydration stimulates the part of the brain that tells you you're thirsty, causing you to drink more liquids. While you can usually correct mild dehydration by drinking more, it may be difficult to keep up with the amount your body needs if you are losing significant amounts of water. Vomiting, diarrhea, or excessive urination or sweating can turn mild dehydration into a serious problem. Brain cells are particularly sensitive to water loss, so mental confusion and even coma may result in severe cases. Blood pressure can fall, causing lightheadedness and overall weakness. If fluid losses continue, internal organs such as the kidneys may be damaged. If prolonged, dehydration may even be fatal.
Drinking water or other fluids is usually the easiest way to replace lost body fluids, but severe cases may need intravenous treatment.
How Common Is Dehydration?
Dehydration can happen to those of any age or gender. However, infants and small children have a high metabolic rate, so relatively large amounts of fluid are required to keep their systems going. The elderly are also at higher risk because their bodies store less water and they tend to drink less fluid on average. Additionally, they may suffer more severe consequences from dehydration than younger adults do. Dehydration is reported as one of the top 10 reasons for hospitalization among Medicare recipients.
Possible Underlying Causes
Dehydration occurs when your body uses or loses more fluid than it takes in. This can result from drinking too little liquid or from excreting too much. Water leaves the body in urine, sweat, and in the air you breathe out. When you have diarrhea, vomit, or sweat too much from a fever or overexertion, the rate of fluid loss can be greater than you can take in new fluids.
Triggers of Dehydration
Dehydration is particularly likely to be triggered by the following factors:
- Insufficient fluid intake
- Repeated vomiting
- Persistent diarrhea
- Excessive sweating from overexertion or fever
- Use of diuretics (also called "water pills") or excessive urination (seen with untreated diabetes, for example)
- Hot environment, such as a heat wave
Diagnosing the Underlying Cause
Your doctor will want to know if you've been vomiting repeatedly, sweating heavily, or had diarrhea. If he or she suspects food poisoning or an infection such as the flu is causing your diarrhea or vomiting, your physician may check you for these conditions. He or she may also investigate to see if you have diabetes, which can cause excessive urination, or take any medications which may contribute to dehydration.
In order to diagnose dehydration, your physician will want to know your recent medical history and have a complete report of any signs or symptoms you have. He or she will perform a physical exam, take your blood pressure, and check your pulse. He or she might also analyze your electrolyte levels with blood and urine tests.
Goals of Treatment
The goal of treatment is to replace lost fluids and make sure your body has enough water and salts. Treatment is also aimed at curing any underlying illness or infection, if possible, or preventing dehydration until illness such as the stomach flu passes.
Drink more fluid. Water is key, but fluids with extra electrolytes can also help. Try flat ginger ale, fruit juices, or specially formulated sports drinks such as Gatorade. Avoid commercially prepared broth or bouillon, since these contain high amounts of salt. Don't consume anything with caffeine in it.
To combat dehydration in remote areas, the World Health Organization developed an oral rehydration solution (ORS) that replaces lost fluids and electrolytes. You can make your own ORS at home from the following recipe:
- 1 quart water
- 1 cup orange juice
- 1 teaspoon table salt
- 1 teaspoon baking powder
- 4 tablespoons sugar
Drugs most commonly used
- Oral rehydration solutions containing electrolytes such as Pedialyte for children, Infalyte for infants, or similar solution for adults
- Intravenous fluids, salts, and nutrients
Considerations for Older People
Dehydration is common among older individuals. If your doctor prescribes any medication for you, be aware that side effects and adverse reactions are more common in older adults. Be sure to remind your physician of any medications you are already taking.
People who have difficulty getting around are more prone to dehydration because it's harder for them to get to water. Keeping an easily accessible glass or pitcher of water or juice will help prevent this.
Considerations for Children and Adolescents
Because dehydration can happen quickly to infants and children, contact your child's pediatrician at any sign of dehydration. If your child is ill, it is critical to ensure that he or she drinks enough fluids. Watch for signs of dehydration: dry mouth, decreased or absent urination, sunken eyes, and reduced or lack of tears. Dehydrated infants may have a severely sunken fontanel (you'll see a soft spot or depression in the front of their forehead or scalp). Check with a doctor before giving your child antidiarrhea medications, which may contain aspirin-like substances that can cause Reye's syndrome, a potentially fatal condition for children. Seek a physician's care for any persistent vomiting or diarrhea.
- Enjoy herbal teas, such as chamomile, mint, ginger, and raspberry.
- Avoid herbs that are diuretics, including dandelion, buchu, juniper, nettle, and uva ursi. Also avoid herbal laxatives, which include aloe, buckthorn, cascara sagrada, rhubarb, and senna. 
Last updated October 1999.
1Castleman, M. The Healing Herbs. New York: Bantam. 1995.
- Prevent dehydration by noticing the color of your urine. It should be almost clear with just a hint of yellow. The less clear it is, the more dehydrated you are.
- Drink six to eight 10-ounce glasses of water or other nonalcoholic and noncaffeinated fluid a day. It's easiest to sip fluids throughout the day, rather than drinking whole glasses at once.
- Once you feel thirsty, you're already dehydrated. Keep drinking so you never feel thirsty.
- Unless you're a competitive athlete, you probably don't need sports drinks. These beverages contain water, sugar, and electrolytes (sodium and potassium). If you want electrolytes, which can be important in severe cases of diarrhea, vomiting, or exertion, just munch pretzels or whole-grain crackers as you drink.
- Don't overexert yourself in hot weather, especially if the relative humidity is low.
- A rapid change in altitude -- flying from Los Angeles to Denver for example -- causes dehydration. So does the air in airplanes -- it's low in humidity. Drink as you fly and upon arrival.
- Avoid alcohol, coffee, tea, colas, and other caffeinated beverages. They're dehydrating.
Additional Preventive Measures
Any time you contract an illness or infection, realize that you are at an increased risk of dehydration. If you become ill, make sure you are drinking plenty of fluids. It's the best way to prevent becoming dehydrated.
- If you get diarrhea, the main risk is dehydration. Increase your fluid intake.
- If an infant or toddler gets diarrhea, give rehydration fluids specially formulated for them, such as Pedialyte and Kaolectrolyte. Also, diluted apple juice can be particularly effective, especially for babies who won't drink their fluids.
When to Call the Doctor
Seek immediate medical help if you have any of the following signs of severe dehydration:
- Rapid drop in weight (several pounds in a few hours or days)
- Muscle contractions or convulsions
- Temperature of 102 F or greater
- Increased heart rate
- Reduced blood pressure
- Fast breathing
- Sunken eyes
- Bloated abdomen
- Skin that takes a long time to return to normal when pinched
- Vomiting/diarrhea that won't go away
- Inability to take anything by mouth
In very severe cases, dehydration may result in hypovolemic shock, which may be confused with other types of shock.
Since dehydration can occur quickly in young children and the elderly people, it is important to seek medical help at even the mildest signs of dehydration. In particular, if you are taking care of a child under age 3, seek medical help if you see the following signs of dehydration:
- Dry mouth and chapped lips
- Severe thirst
- Lightheadedness or weakness
- Skin that takes a long time to return to normal when pinched
- Darkened or decreased urination (fewer wet diapers than usual)
- Crying with few or no tears
- Prolonged vomiting or diarrhea; can't keep fluids down or won't drink
Websites & Organizations
American Diabetes Association
1660 Duke Street
Alexandria, VA 22314
Phone: 703-549-1500 or 800-342-2383
American Dietetic Association
216 West Jackson Blvd., Ste. 800
Chicago IL 60606-6995
American Digestive Health Foundation
7910 Woodmont Avenue, 7th Floor
Bethesda, MD 20814-3015
American Thyroid Association
Walter Reed Army Medical Center
Washington, DC 20307-5001
Phone: 202-882-7717 or 800-542-6687
Food and Drug Administration
5630 Fishers Lane, Room 1061
Rockville, MD 20852
Juvenile Diabetes Foundation International
432 Park Avenue South
New York, NY. 10016-8013
National Digestive Diseases Information Clearinghouse
2 Information Way
Bethesda, MD 20892-3570
Sources & Further Reading
Bennett, J. Claude and Plum, Fred. Cecil Textbook of Medicine, eds. Philadelphia: W. B. Saunders, 1996.
Castleman, M. The Healing Herbs. New York: Bantam. 1995.
Fauci, Anthony J., et. al. Harrison's Principles of Internal Medicine, eds. New York: McGraw-Hill, 1998.
Hurst, J. Willis. Medicine for the Practicing Physician eds. Stamford, CT: Appleton & Lange 1996.
Noble, John. Primary Care Medicine ed. St. Louis: Mosby, 1996.
Physicians' Desk Reference. Montvale, NJ: Medical Economics Co., 1998.
Rakel, Robert E. Conn's Current Therapy eds. Philadelphia: W.B. Saunders, 1998.
Taylor, Robert B. Family Medicine: Principles and Practice. New York: Springer-Verlag, 1998.
Tierney, L.M., McPhee, S.J., and Papadakis, M.A. Current Medical Diagnosis and Treatment eds. Stamford, CT: Appleton & Lange, 1998.
Greenleaf, JE. "Problem: Thirst, Drinking Behavior, and Involuntary Dehydration." Med Sci Sports Exerc. 24(6):645-56. Jun 1992.
Grisanti, KA, Jaffe, DM. "Dehydration Syndromes. Oral Rehydration and Fluid Replacement." Emerg Med Clin North Am. 9(3):565-88. Aug 1991.
Jackonen, S "Dehydration and Hydration in the Terminally Ill: Care Considerations." Nurs Forum. 32(3):5-13. Jul-Sep 1997.
Mackenzie, A, Barnes, G, Shann, F. "Clinical Signs of Dehydration in Children." Lancet. 2(8663):605-7. Sep 9, 1989
Murray, R. "Rehydration Strategies--Balancing Substrate, Fluid, and Electrolyte Provision." Int J Sports Med, 19 Suppl. 2():S133-5. Jun 1998.
Musgrave, CF. "Terminal Dehydration. To Give or Not to Give Intravenous Fluids?" Cancer Nurs. 13(1):62-6. Feb 1990.
Noakes, TD. "Dehydration During Exercise: What Are the Real Dangers?" Clin J Sport Med. 5(2):123-8. 1995.
Nunneley, S, Stribley, R. "Heat and Acute Dehydration Effects on Acceleration Response in Man." J Appl Physiol. 47(1):197-200. Jul 1979.
Warren, JL, Bacon, WE, Harris, T, McBean, AM, Foley, DJ, Phillips, C. "The Burden and Outcomes Associated with Dehydration Among US Elderly, 1991." Am J Public Health. 84(8):1265-9. Aug 1994.
Whitehead, FJ, Couper, RT, Moore, L, Bourne, AJ, Byard, RW. "Dehydration Deaths in Infants and Young Children." Am J Forensic Med Pathol. 17(1):73-8. Mar 1996.