What Is Dehydration?

Dehydration is a condition that occurs when someone loses more fluids than he or she takes in. Dehydration isn't as serious a problem for teens as it can be for babies or young children. But if you ignore your thirst, dehydration can slow you down.

Our bodies are about two thirds water. When someone gets dehydrated, it means the amount of water in his or her body has dropped below the level needed for normal body function. Small decreases don't cause problems, and in most cases, they go completely unnoticed. But losing larger amounts of water can sometimes make a person feel quite sick.

Causes of Dehydration

One common cause of dehydration in teens is gastrointestinal illness. When you're flattened by a stomach bug, you lose fluid through vomiting and diarrhea.

You might also hear that you can get dehydrated from playing sports. In reality, it's rare to reach a level of even moderate dehydration during sports or other normal outdoor activity. But if you don't replace fluid you lose through sweat as you go, you can become dehydrated from lots of physical activity, especially on a hot day.

Some athletes, such as wrestlers who need to reach a certain weight to compete, dehydrate themselves on purpose to drop weight quickly before a big game or event by sweating in saunas or using laxatives or diuretics, which make a person go to the bathroom more. This practice usually hurts more than it helps, though. Athletes who do this feel weaker, which affects performance. They can also have more serious problems, like abnormalities in the salt and potassium levels in the body. Such changes can also lead to problems with the heart's rhythm.

Dieting can sap someone's water reserves as well. Beware of diets or supplements, including laxatives and diuretics that emphasize shedding "water weight" as a quick way to lose weight. Losing water weight is not the same thing as losing actual fat.

Signs of Dehydration

To counter dehydration, you need to restore the proper balance of water in your body. First, though, you have to recognize the problem.

Thirst is one indicator of dehydration, but it is not an early warning sign. By the time you feel thirsty, you might already be dehydrated. Other symptoms of dehydration include:

• feeling dizzy and lightheaded
• having a dry or sticky mouth
• producing less urine and darker urine

As the condition progresses, a person will start to feel much sicker as more body systems (or organs) are affected by the dehydration.

Preventing Dehydration

The easiest way to avoid dehydration is to drink lots of fluids, especially on hot, dry, windy days. Water is usually the best choice. Drinking water does not add calories to your diet and can be great for your health.

The amount that people need to drink will depend on factors like how much water they're getting from foods and other liquids and how much they're sweating from physical exertion.

When you're going to be outside on a warm day, dress appropriately for your activity. Wear loose-fitting clothes and a hat if you can. That will keep you cooler and cut down on sweating. If you do find yourself feeling parched or dizzy, take a break for a few minutes. Sit in the shade or someplace cool and drink water.

Sports and Exercise

If you're participating in sports or strenuous activities, drink some fluids before the activity begins. You should also drink at regular intervals (every 20 minutes or so) during the course of the activity and after the activity ends. The best time to train or play sports is in the early morning or late afternoon to avoid the hottest part of the day.

Gastrointestinal Infections

If you have a stomach bug and you're spending too much time getting acquainted with the toilet, you probably don't feel like eating or drinking anything. But you still need fluids. Take lots of tiny sips of fluids. For some people, ice pops may be easier to tolerate.

Caffeine

Caffeine is a diuretic, meaning it causes a person to urinate (pee) more. It's not clear whether this causes dehydration or not, but to be safe, it's probably a good idea to stay away from too much caffeine in hot weather, during long workouts, or in other situations where you might sweat a lot.

When to See a Doctor

Dehydration can usually be treated by drinking fluids. But if you faint or feel weak or dizzy every time you stand up (even after a couple of hours) or if you have very little urine output, you should tell an adult and visit your doctor. The doctor will probably look for a cause for the dehydration and encourage you to drink more fluids.

If you're more dehydrated than you realized, especially if you can't hold fluids down because of vomiting, you may need to receive fluids through an IV to speed up the rehydration process. An IV is an intravenous tube that goes directly into a vein.

Occasionally, dehydration might be a sign of something more serious, such as diabetes, so your doctor may run tests to rule out any other potential problems.

In general, dehydration is preventable. So just keep drinking that H2O for healthy hydration.

Reviewed by: Steven Dowshen, MD
Date reviewed: May 2009