Rehydration in children: how to do it?

1. Understanding a child's hydration needs

A child is growing rapidly, which implies specific needs for nutrients and water. The European Food Safety Authority has established reference intakes to follow for hydration :

These are recommendations to meet water needs under moderate ambient temperature conditions and normal physical activity . These values ​​are minimum thresholds and may be insufficient in hot weather, for example. It is therefore important to ensure that children have regular access to water so they can drink as soon as they feel thirsty. Overweight or obese children may also have higher water requirements .

Furthermore , it is important to know the signs of dehydration in infants and children in order to intervene quickly and restore hydration . Because infants cannot yet identify and express their water needs, they require special attention from those around them. Here are the symptoms to be aware of in infants:

• Dry mouth, often accompanied by a lack of saliva. The appearance of the lips can help identify it.
• Less wet diapers or the need to change fewer than 4 diapers per day.
• An abnormal depression of the anterior fontanelle (soft area on the head).
• Crying without tears .
• Unusual drowsiness or irritability.

These signs change as the child grows (from 2 to 7 years old). Even if they can express their thirst or symptoms more easily, it's still important to remain vigilant in the following cases:

• An intense thirst.
• Very dark and infrequent urine.
• Dizziness and fatigue .
• Dry eyes, dark circles or sunken eyes.
• Confusion and abnormal irritability.
• Sticky or dry oral mucous membranes (tongue, lips).

A sudden loss of weight. In children, dehydration can occur with a loss of as little as 2% of body weight, and becomes severe beyond 5%. When the loss exceeds 10%, the situation is critical: the functioning of vital organs is compromised , requiring urgent medical attention .

2. Common causes of dehydration in children

Certain situations put children at high risk of dehydration. The main causes are excessive fluid loss or insufficient water intake.

Diarrhea and vomiting , common in cases of gastroenteritis, are among the most concerning symptoms. These rapid digestive losses lead to a significant depletion of water and electrolytes. However, in children, the sensation of thirst is not always sufficient to spontaneously compensate for these losses. It is therefore important and essential to encourage them to drink. At the same time, it is crucial not to interrupt their diet: a balanced and appropriate diet remains vital to limit the associated risks of malnutrition. It is therefore best to avoid foods that are difficult to digest or have a laxative effect, such as certain green vegetables or acidic fruits. Instead, favor anti-diarrheal foods, such as rice, ripe bananas, and applesauce.

Another major cause of dehydration is sweating . It naturally increases during intense physical activity and in hot weather. As long as the child has easy access to water and feels thirsty, these losses can be replenished . However, fever can also lead to excessive sweating . In this context, the sensation of thirst may no longer be sufficient and could seem less important compared to other symptoms. It is then necessary to encourage regular hydration , even in small amounts.

Ultimately, the simplest cause of dehydration is insufficient water intake . This can be due to a child underestimating their thirst, or not having a drink available and going without. It is therefore important to offer them water regularly, even if they don't complain, and above all, to teach them to recognize the signs of thirst or fatigue associated with dehydration.

3. Types of rehydration

There are several ways to rehydrate, which vary in their effectiveness, ease of use, and taste acceptability.

3.1 Oral rehydration (first-line solution)

First, there are oral rehydration solutions (ORS). These rely on the ingestion of a solution containing water, electrolytes (notably sodium, potassium, and chloride), and glucose. These elements facilitate water absorption by the intestine via the sodium-glucose cotransporter (SGLT1). They are an essential solution in cases of moderate to severe dehydration , when drinking water alone is no longer sufficient, or when the required volumes would be too large to be well tolerated.

They are therefore recommended for infants, who are more vulnerable and can be difficult to rehydrate, especially after gastroenteritis, which is responsible for significant losses of water and electrolytes. However, they can be useful at any age as soon as dehydration becomes visible, especially in aggravating circumstances (high heat for example).

If you do not have ready-made ORS, it is possible to prepare a simple homemade solution (recommended by the WHO):

The ingredients are:

• 1 liter of water
• 1 teaspoon of salt
• 6 teaspoons of sugar

3.2 Intravenous rehydration (severe cases)

In cases of moderate to severe dehydration, and when oral rehydration is impossible or insufficient (inability to drink, excessive fluid losses, marked electrolyte imbalance ), intravenous rehydration may be implemented in the hospital.

Once a healthcare professional has determined that this method is necessary, the patient is placed on an IV drip. A solution composed of water, glucose, and electrolytes is slowly administered into the bloodstream . The patient is then closely monitored to prevent fluid overload and to assess the evolution of their condition.

This method of rehydration bypasses the digestive system, which is particularly useful in cases of digestive disorders or impaired absorption. Furthermore, monitoring allows for precise control of blood water and electrolyte levels , something that cannot be done at home.

But be aware, this method remains reserved for hospital settings or emergency care, with well-defined indications.

4. Recommended practices regarding hydration in children 

Besides oral rehydration solutions (ORS), other methods can effectively help maintain or restore good hydration in children. First, encourage frequent drinking of small amounts of water ; this is more enjoyable, but requires careful attention and constant reminders!

Include foods rich in water. Certain foods can supplement your fluid intake:

• Fresh fruit (watermelon, melon, orange, strawberries),

• Vegetables (cucumber, tomato, courgette),

• Light broths and soups , which are particularly appreciated in cases of fatigue or loss of appetite.

However, keep in mind that not all drinks are equal when it comes to hydration: sodas or concentrated juices will be less effective than still water or a watermelon.

5. Prevention of dehydration in children

As the saying goes, prevention is better than cure. By establishing good hydration habits from a young age, you significantly reduce the risk of dehydration.

Make sure your child develops good daily habits. They should always have a water bottle or glass of water within reach, especially on hot days or during physical activity. Teach them to drink regularly , even if they don't feel thirsty, such as when they have a fever , or after vomiting or diarrhea , when fluid and electrolyte loss is increased. Finally, encourage them to listen to their body: unusual fatigue, a dry mouth, darker urine, or headaches can be early signs of dehydration. Encourage them to tell you as soon as they experience these symptoms.

For your part, learn the first signs of dehydration so you can react as quickly as possible!

Keeping young children hydrated is an important issue , but one that everyone can address. By encouraging good habits and ensuring they stay hydrated, dehydration can be prevented most of the time . However, if you notice signs of dehydration, you can take action with a diet rich in water, regular hydration, and sometimes specialized hydration solutions . For moderate to severe cases, oral rehydration solutions (ORS) and professional advice will be invaluable.

Bibliography

EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA); Scientific Opinion on Diet reference values ​​for water. EFSA Journal 2010; 8(3):1459. [48 pp.]. https://doi.org/10.2903/j.efsa.2010.1459

Sentongo TA (2004). The use of oral rehydration solutions in children and adults. Current gastroenterology reports, 6(4), 307–313. https://doi.org/10.1007/s11894-004-0083-5