Every day, we lose body fluids (water and other liquids) by urinating (peeing) and sweating. We replace the lost fluids by eating and drinking. Normally, the body balances these processes carefully, so we replace as much water as we lose. Certain minerals, such as sodium, potassium, and chloride, are also involved in keeping a healthy fluid balance.

Dehydration (say: dee-hi-DRAY-shun) happens when more fluid leaves the body than enters it. This can happen when a child does not drink enough fluid or when he loses more body fluid than usual. The imbalance results in dehydration.

Dehydration can happen slowly or quickly, depending on how the fluid is lost and the age of the child. Younger children and babies are more likely to become dehydrated, because their bodies are smaller and they have smaller fluid reserves. Older children and teens can handle minor fluid imbalances better.

Causes of dehydration

The most common causes of dehydration are:

poor fluid intake during an illness
fluid losses from diarrhea and/or vomiting

Healthy children can vomit or have loose stools once in a while without becoming dehydrated. But dehydration can occur suddenly and be very dangerous, especially for babies and young children. If children are vomiting, have watery stools, and are not able to drink, they can lose fluids quickly and become very sick.

Common signs and symptoms of dehydration

Your child may show one or more of the following symptoms of dehaydration:

restlessness, drowsiness, irritability
cold or sweaty skin
low energy levels, seeming very weak or limp
no tears when crying
dry sticky mouth and/or tongue
sunken eyes or sunken soft spot (fontanelle) on baby’s head
smaller amounts of urine, no urine over 8 to 12 hours, or dark-coloured urine

Measuring dehydration

Ideally, we would measure dehydration by carefully weighing the sick child and comparing this weight to the child's weight before he became sick. The difference between the two weights would be the amount of fluid the child has lost. However, this is often not possible: different scales give slightly different weights, and there is usually no accurate weight measurement from just before the child became sick.

The Clinical Dehydration Scale is used by health professionals to determine the severity of dehydration. You can use it as well. Using this scale can help to guide you as to whether your child is getting better, staying the same, or getting worse. A doctor may use more findings to assess dehydration, but this scale is a good place to start.

The chart assigns points for certain signs or symptoms you observe in your child. The higher the point total, the worse the dehydration.

To calculate your child's dehydration status:

Mark down your child's symptoms.
For each symptom, find the point value in the chart.
Add up the points and determine the score.

For example, if your child has dry mucous membranes (2 points), decreased tears (1 point), and a sweaty appearance (2 points), the total point value is 5 points. A score of 5 points means your child has moderate to severe dehydration.

Clinical Dehydration Scale

	0	1	2
General appearance	Normal	Thirsty, restless, or lethargic but irritable when touched	Drowsy, limp, cold, sweaty
Eyes	Normal	Slightly sunken	Very sunken
Mucous membranes*	Moist	Sticky	Dry
Tears	Present	Decreased	Absent

*Mucous membranes include the moist lining of the mouth and the eyes.

Score of 0 = no dehydration

Score of 1 to 4 = some dehydration

Score of 5 to 8 = moderate to severe dehydration

(Goldman 2008)

Treatment of dehydration

The treatment of dehydration is based on how dehydrated your child is.

Moderate to severe dehydration (score of 5 to 8 on the Clinical Dehydration Scale)

Take your child to see a doctor for assessment and treatment right away.

Mild dehydration (score of 1 to 4 on the Clinical Dehydration Scale)

Offer your child oral rehydration solution to replace the water and salts your child has lost. Commercially available oral rehydration solutions such as Pedialyte, Gastrolyte, Enfalyte or other brands contain a properly balanced amount of water, sugars, and salts to promote absorption of the fluid. It is best to use these products, rather than plain water or home-made solutions, especially for babies and young children.

Give your child 5 mL (1 teaspoon) every 5 minutes and increase as tolerated up to 30 mL (1 ounce) every 5 minutes. Aim for 25 to 50 mL per kilogram of body weight over 1 to 2 hours. This means that if your child weighs 13 kg (29 lb), you would aim to give a total of 325 to 650 mL (11 to 22 ounces) of oral rehydration solution over 1 to 2 hours.

If your baby is breastfeeding, continue to breastfeed.

No dehydration (score of 0 on the Clinical Dehydration Scale)

Continue to offer your child fluids and an age-appropriate diet. If your child has vomiting or diarrhea, give 10 mL/kg of an oral rehydration solution for each diarrhea or vomiting episode. Continue to offer your child small frequent feedings.

Treatment after rehydration

Once your child is better hydrated, the next step is to work toward getting him back to what he normally eats. This can usually happen about 4 to 6 hours after the last episode of vomiting. Offer your child the usual foods and drinks he enjoys.

You do not need to give your child a restrictive diet such as BRAT (bananas, rice, apple sauce, toast). However, avoid offering your child foods that have a high sugar or sweet content, fried or high-fat foods, and spicy foods until he has recovered.

Do not dilute your child's formula or milk with water, oral rehydration solution, or any other fluid.

If your child has ongoing vomiting or diarrhea, give 10 mL/kg of an oral rehydration solution for each stool or vomiting episode. You can also offer him the usual foods and drinks he enjoys. Even if there is diarrhea, it is usually better to continue offering milk and other nutritious foods your child’s body needs to recover and to heal.

Preventing future episodes with oral rehydration solution

You can prevent dehydration by offering your child oral rehydration solution often and as soon as you notice the dehydration symptoms. These solutions are available at pharmacies in ready-to-serve liquids, popsicles, and powders. Powders are easier to store and have longer expiration dates, but they have to be mixed very carefully or the wrong strength (concentration) can be given.

If your child refuses the oral rehydration solution by bottle or cup, give the solution using a teaspoon or syringe. The temperature of the solution does not matter. You can mix the solution with warm, cool, or room-temperature liquids, whichever your child prefers.

When to see a doctor

Make an appointment with your child’s regular doctor if:

your child refuses to take oral rehydration solution
your child persistently vomits

Go to the nearest Emergency Department or call 911 if:

your child does not appear to be recovering or is becoming more dehydrated
there is blood in the diarrhea or vomit, or the vomit turns green in colour
your child has pain that you cannot manage easily or that is making him unable to take in enough fluids
diarrhea is lasting more than 10 days