Diseases & Conditions

Dehydration

Dehydration occurs when you lose more fluid than you take in, and your body doesn't have enough water and other fluids to carry out its normal functions. If you don't replenish lost fluids, you may suffer serious consequences.

Common causes of dehydration include intense diarrhea, vomiting, fever or excessive sweating. Inadequate intake of water during hot weather or exercise also may cause dehydration. Anyone may become dehydrated, but young children, older adults and people with chronic illnesses are most at risk.

You can usually reverse mild to moderate dehydration by increasing your intake of fluids, but severe dehydration needs immediate medical treatment. The safest approach is prevention of dehydration. Monitor your fluid loss during hot weather, illness or exercise, and drink enough liquids to replace what you lose.

Mild to moderate dehydration is likely to cause:

• Dry, sticky mouth
• Sleepiness or tiredness — children are likely to be less active than usual
• Thirst
• Decreased urine output — fewer than six wet diapers a day for infants and eight hours or more without urination for older children and teens
• Few or no tears when crying
• Muscle weakness
• Headache
• Dizziness or lightheadedness

Severe dehydration, a medical emergency, can cause:

• Extreme thirst
• Extreme fussiness or sleepiness in infants and children; irritability and confusion in adults
• Very dry mouth, skin and mucous membranes
• Lack of sweating
• Little or no urination — any urine that is produced will be dark yellow or amber
• Sunken eyes
• Shriveled and dry skin that lacks elasticity and doesn't "bounce back" when pinched into a fold
• In infants, sunken fontanels — the soft spots on the top of a baby's head
• Low blood pressure
• Rapid heartbeat
• Fever
• In the most serious cases, delirium or unconsciousness

Unfortunately, thirst isn't always a reliable gauge of the body's need for water, especially in children and older adults. A better barometer is the color of your urine: Clear or light-colored urine means you're well hydrated, whereas a dark yellow or amber color usually signals dehydration.

When to see a doctor
If you're a healthy adult, you can usually treat mild to moderate dehydration by drinking more fluids. Get immediate medical care if you develop severe signs and symptoms such as extreme thirst, no urination for eight hours, shriveled skin, dizziness and confusion.

Treat children and older adults with greater caution. Call your family doctor right away if your child:

• Develops severe diarrhea, with or without vomiting or fever
• Has had episodes of vomiting for more than eight hours
• Has had moderate diarrhea for three days or more
• Can't keep down fluids
• Is irritable or disoriented and much sleepier or less active than usual
• Has any of the signs or symptoms of mild or moderate dehydration

Go to the nearest hospital emergency room or call 911 or your emergency medical number if you think a child or older adult is severely dehydrated. You can help prevent dehydration from becoming severe by carefully monitoring someone who is sick and giving fluids at the first sign of diarrhea, vomiting or fever and by encouraging children to drink plenty of water before, during and after exercise.

Your doctor can often diagnose dehydration on the basis of physical signs and symptoms such as little or no urination, sunken eyes, and skin that lacks its normal elasticity and resilience when pinched. If you're dehydrated, you're also likely to have low blood pressure, especially when moving from a prone to a standing position, a faster than normal heart rate and reduced blood flow to your extremities.

To help confirm the diagnosis and pinpoint the degree of dehydration, you may have other tests, such as:

• Blood tests. These may be used to check your electrolytes, especially sodium and potassium; to look for signs of concentrated blood; and to evaluate how well your kidneys are working.
• Urinalysis. The color and clarity of your urine, the presence of carbon compounds (ketones) and your urine's specific gravity — that is, the mass of the urine as compared with equal amounts of distilled water — all help show whether you're dehydrated and to what degree. A high specific gravity, for example, indicates significant dehydration.

If it's not obvious why you're dehydrated, your doctor may order additional tests to check for diabetes and for liver or kidney problems.

The only effective treatment for dehydration is to replace lost fluids and lost electrolytes. The best approach to dehydration treatment depends on your age, the severity of your dehydration and its cause.

Treating dehydration in sick children
Your doctor can offer specific suggestions for treating dehydration in your child, but some general guidelines include the following:

• Use an oral rehydration solution. Unless your doctor advises otherwise, use an oral rehydration solution such as Pedialyte for infants and children who have diarrhea, vomiting or fever. These solutions contain water and salts in specific proportions to replenish both fluids and electrolytes. They also contain glucose or another carbohydrate such as rice powder to enhance absorption in the intestinal tract. Oral rehydration products are readily available in most drugstores, and many pharmacies carry their own brands. Begin giving fluids early in the course of an illness instead of waiting until the situation becomes urgent.

  In most developing countries, you can buy packets of a powdered oral rehydration solution, WHO-ORS, originally developed by the World Health Organization to treat diarrhea and dehydration in infants with cholera. Reconstitute the powder in water according to the directions on the package. Always purify the water first by boiling, filtration or other proven methods. Remeasure the water, then add the powdered oral rehydration material.

  In an emergency situation where a pre-formulated solution is unavailable, you can make your own oral rehydration solution by mixing 1/2 teaspoon salt, 1/2 teaspoon baking soda, 3 tablespoons sugar and 1 liter (about 1 quart) of safe drinking water. Be sure to measure accurately because incorrect amounts can make the solution less effective or even harmful. If possible, have someone else check your measurements for accuracy.

  Whatever alternative you chose, be sure to give enough solution. Your doctor may suggest specific amounts, depending on your child's age and degree of dehydration, but a general rule of thumb is to keep giving liquids slowly until your child's urine becomes clear in color. When your child is vomiting, try giving small amounts of solution at frequent intervals — 1 teaspoon every minute, for instance. If your child can't keep this down, wait 30 to 60 minutes and try again. Room temperature fluids are best.

• Continue to breast-feed. Don't stop breast-feeding when your baby is sick, but add an oral rehydration solution as well. If you give your baby formula, try switching to one that's lactose-free until diarrhea improves — lactose can make diarrhea worse. Never dilute formula more than the instructions advise. Your doctor may also suggest substituting an oral rehydration solution for the formula for 12 to 24 hours.
• Avoid certain foods and drinks. The best liquid for a sick child is an oral rehydration solution — plain water doesn't provide essential electrolytes, and although sports drinks replenish electrolytes, they replace those lost through sweating, not through diarrhea or vomiting. Avoid giving your child salty broths, milk — especially boiled milk — sodas, fruit juices or gelatins, which don't relieve dehydration and which may make symptoms worse.

Treating dehydration in sick adults
Most adults with mild to moderate dehydration from diarrhea, vomiting or fever can improve their condition by drinking more water. Avoid coffee, tea and other beverages that contain caffeine, as they may temporarily increase dehydration. Fruit juices and sodas can make diarrhea worse.

Treating dehydration in athletes of all ages
For exercise-related dehydration, cool water is your best bet. Sports drinks containing electrolytes and a carbohydrate solution also may be helpful. There's no need for salt tablets — too much salt can lead to hypernatremic dehydration, a condition in which your body not only is short of water but also carries an excess of sodium.

Treating severe dehydration
Children and adults who are severely dehydrated should be treated by emergency personnel arriving in an ambulance or in a hospital emergency room, where they can receive salts and fluids through a vein (intravenously) rather than by mouth. Intravenous hydration provides the body with water and essential nutrients much more quickly than oral solutions do — something that's essential in life-threatening situations.