What Is Dehydration?

Dehydration is 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.

When someone gets dehydrated, it means the amount of water in the 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 not drinking enough to keep up with the loss of fluid can sometimes make a person feel quite sick.

What Causes 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. On top of that, you probably don't feel very much like eating or drinking.

Even if you don't have a stomach virus, you can get dehydrated for other reasons when you're sick. For example, if you have a sore throat, you might find it hard to swallow food or drinks. And if you have a fever, water evaporates from your skin in an attempt to cool your body down.

You also can get dehydrated from from lots of physical activity (like during sports). If you don't replace the fluid you lose through sweat as you go, you can get dehydrated, especially on a hot day. Even mild dehydration can affect an athlete's physical and mental performance.

What Are the Signs and Symptoms 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
  • peeing less and darker pee

If dehydration continues, a person will start to feel much sicker as more body systems (or organs) are affected.

How Is Dehydration Treated?

It's important to know the early signs of dehydration and to respond quickly if you have them. The goal in treating dehydration is to replace fluids and restore body fluids to normal levels.

If you're mildly dehydrated from lots of activity, you'll be thirsty and should drink as much as you want. Plain water is the best option. Then rest in a cool, shaded spot until the lost fluid has been replaced.

Can Dehydration Be Prevented?

The easiest way to avoid dehydration is to drink lots of fluids, especially water, especially on hot days. Drinking water does not add calories to your diet and is great for your health.

The amount that people need to drink will depend on things like age, size, level of physical activity, and the weather.

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 and 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. Then drink at regular intervals (every 20 minutes or so) during the course of the activity and after it ends. The best time to train or play sports is in the early morning or late afternoon or evening 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 frequent, small sips of fluids. For some people, ice pops may be easier to tolerate.


Caffeine is a diuretic, meaning it causes a person to 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 Should I Call the Doctor?

Dehydration can usually be treated by drinking fluids (water). But if you can't hold down any fluids; feel faint, weak, or dizzy; or are peeing much less than usual, you should tell an adult and visit your doctor.

If you're more dehydrated than you realized, especially if you can't hold fluids down because of vomiting, you may need to get fluids through an IV (into a vein) at a hospital to speed up the rehydration process.

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.

Dehydration is often preventable. So don't ignore your thirst and keep drinking that H2O for healthy hydration.

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