What Is Dehydration?

We all lose some body water every day in our sweat, tears, urine (pee), and stool (poop). Water also evaporates from skin and leaves the body as vapor when we breathe. We usually replace this body fluid and the salts it contains through our regular diet.

Sometimes, kids lose large amounts of water and salts. This can happen when they have a fever, diarrhea, or vomiting, or through long periods of exercise with lots of sweating. And some illnesses can make it hard for them to drink fluids.

If they can't replace the fluid that's been lost, kids can become dehydrated.

What Are the Signs and Symptoms of Dehydration?

If your child has a fever, diarrhea, or vomiting, or is sweating a lot on a hot day or during intense physical activity, watch for signs of dehydration. These include:

  • a dry or sticky mouth
  • few or no tears when crying
  • eyes that look sunken
  • in babies, the soft spot (fontanelle) on top of the head looks sunken
  • peeing less or fewer wet diapers than usual
  • dry, cool skin
  • irritability
  • drowsiness or dizziness

How Is Dehydration Treated?

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

Kids who are mildly dehydrated from lots of activity will probably be thirsty and should drink as much as they want. Plain water is the best option. They should rest in a cool, shaded spot until the lost fluid has been replaced.


Kids with mild to moderate dehydration due to diarrhea from an illness (like gastroenteritis) should have their lost fluids replaced. This is known as rehydration. It's done by giving a special liquid called an oral rehydration solution (ORS) over the course of 3 to 4 hours.

ORS is available in many grocery stores and drugstores without a prescription. It has the right combination of sugar and salts that dehydrated kids need.

Start the rehydration process by giving your child 1 or 2 teaspoons (5 or 10 milliliters) of an ORS every few minutes. You can use a spoon or an oral syringe. This may not seem like enough fluids to rehydrate your child, but these small amounts can add up to more than a cup (237 milliliters) an hour. If your child does well, you can gradually give bigger sips a little less often.

Even kids who are vomiting can usually be rehydrated this way because the small frequent sips get absorbed in between the vomiting episodes.

A breastfed infant should continue to be nursed, even during rehydration, unless vomiting repeatedly. Give the ORS in between feedings. Stop giving formula to a formula-fed baby during rehydration, and restart as soon as your baby can keep fluids down and isn't showing signs of dehydration.

Do not give a dehydrated child water, soda, ginger ale, tea, fruit juice, gelatin desserts, or chicken broth. These don't have the right mix of sugar and salts and can make diarrhea worse. Older kids who are dehydrated can have sports drinks, but oral rehydration solution is best for young children and infants.

When your child is rehydrated, you can serve a normal diet, including breast milk, formula, or milk.

Some dehydrated kids do not improve when given an ORS, especially if they have explosive diarrhea (very frequent BMs that are forceful and very loud) or are vomiting often. When fluid losses can't be replaced for these or other reasons, a child might need to get intravenous (IV) fluids in the hospital.

If you're treating your child for dehydration at home and feel that there's no improvement or that the dehydration is getting worse, call your doctor right away or take your child to the nearest emergency room (ER).

Can Dehydration Be Prevented?

Making sure kids get plenty of fluids when they're sick or physically active can help protect them from getting dehydrated.

How to keep them hydrated can depend. For example, a child with a sore throat may become dehydrated because drinking or eating is too painful. Easing the pain with acetaminophen or ibuprofen may help, and cold drinks or popsicles can soothe a burning throat while also giving fluids.

Not all fevers need to be treated, but if your child is uncomfortable and not getting enough fluids, you can give acetaminophen or ibuprofen to help control the fever.

It's important that kids drink often during hot weather. Those who play sports or are very physically active should drink extra fluids beforehand, and then take regular drink breaks (about every 20 minutes) during the activity. Ideally, sports practices and competitions should be held in the early morning or late afternoon to avoid the hottest part of the day.

Thirst is not a good early sign of dehydration. By the time they feel thirsty, kids might already be dehydrated. That's why they should start drinking before they feel thirsty and have more fluids even after thirst is quenched.

Dehydration and the "Stomach Flu"

Kids with mild gastroenteritis (also called the "stomach flu") who aren't dehydrated should still drink extra fluids to replace those lost from vomiting and diarrhea. Most kids can safely eat their regular diet while they're sick.

Infants with mild gastroenteritis who aren't dehydrated should continue getting breast milk or regular-strength formula. Older kids may continue to drink full-strength milk and other fluids.

Foods that are usually well tolerated by kids with gastroenteritis who aren't dehydrated include: complex carbohydrates (such as rice, wheat, potatoes, bread, and cereals), lean meats, yogurt, fruits, and vegetables. Avoid fatty foods or foods high in sugars (including juices and soft drinks).

If your child is vomiting and isn't dehydrated, give fluids often, but in small amounts.

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Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.