Rehydration in children: how to do it?

1. Understanding the child's water needs

A child is growing, which means specific nutrient and water needs. The European Food Safety Authority has established nutritional reference values ​​to follow for hydration :

These are recommendations for meeting water needs in moderate ambient temperatures and during normal physical activity. These values ​​are minimum thresholds, which may be insufficient in cases of extreme heat, for example. It is therefore important to ensure that children have regular access to water so that they can drink it as soon as they feel the need. In overweight or obese children, water needs may also be higher.

Additionally, the signs of dehydration in infants and children are important to know so that you can intervene quickly and restore hydration. Since 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:

• A 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 sleepiness or irritability.

These signs evolve as the child grows (from 2 to 7 years old). Even if he or she can express his or her thirst or symptoms more easily, it is still important to remain vigilant in the following cases:

• An intense thirst .
• Very dark and infrequent urine.
• Dizziness and fatigue.
• Dry, dark-circled or sunken eyes.
• Abnormal confusion and irritability.
• Sticky or dry oral mucous membranes (tongue, lips).

A sudden weight loss. In children, dehydration can occur as early as a 2% loss of body weight, and becomes severe beyond 5%. When the loss exceeds 10%, the situation is critical: the function 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 water loss or insufficient water intake.

Diarrhea and vomiting, common in cases of gastroenteritis, are among the most worrying causes. These rapid digestive losses lead to a significant loss 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, feeding should not be interrupted: a balanced and appropriate diet remains crucial to limit the associated risks of malnutrition. It is therefore preferable to avoid foods that are difficult to digest or laxatives, 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 high temperatures. As long as the child has easy access to water and feels thirsty, these losses can be compensated . However, fever can also cause 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 consumption. It can be as simple as a child underestimating their thirst, or not having a drink available and doing without. It's therefore important to offer them water regularly, even if they don't complain, and especially to teach them to recognize the signs of thirst or fatigue linked to dehydration.

3. Types of rehydration

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

3.1 Oral rehydration (first-line solution)

First, there are oral rehydration solutions (ORS). These solutions involve ingesting a solution containing water, electrolytes (particularly sodium, potassium, and chloride), and glucose. These elements facilitate the absorption of water from the intestine via sodium-glucose cotransport (SGLT-1). They are an essential solution in cases of moderate to severe dehydration, when water consumption 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, particularly 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 the event of aggravating circumstances (extreme heat, for example).

If you don't have ready-made ORS, you can 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 water loss, marked electrolyte imbalance ), intravenous rehydration can be implemented in hospital.

Once a healthcare professional has determined that this method is necessary, the patient is then 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 avoid fluid overload and to monitor the progress of their condition.

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

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

4. Recommended practices regarding hydration in children 

Besides ORS, other methods can effectively help maintain or restore good hydration in children. First, encourage frequent intake of small amounts of water. This is more pleasant, but requires special attention and constant reminders!

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

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

• Vegetables (cucumber, tomato, zucchini),

• 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 plain water or watermelon.

5. Prevention of dehydration in children

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

Make sure your child adopts good habits every day. They should always have a water bottle or glass of water within reach, especially on hot days or during physical activities. Teach them to drink regularly, even when they don't feel thirsty, such as during a fever, or after vomiting or diarrhea, when fluid and electrolyte losses are increased. Finally, teach them to listen to their body: unusual fatigue, a dry mouth, darker urine, or headaches can be early signs of dehydration. Encourage them to talk to you as soon as they experience them.

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

Hydration for young children is an important issue, but it's accessible to everyone. By getting them to adopt good habits and ensuring their hydration, it's possible to avoid dehydration most of the time. However, if you notice signs, you can take action with a water-rich diet, regular hydration, and sometimes specialized hydration solutions. For moderate to severe cases, ORS and professional advice will be of great help.

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