Thirst is defined as a physiological need to drink or the feeling that there is a need to drink. Regulation of the body’s intake of fluid occurs in the brain, which sends signals throughout the body that fluid is needed. When there is not enough fluid in the body, dehydration occurs.

Beside thirst, other symptoms of dehydration include dry mouth; rough, dry skin; weight loss; weakness, light headedness and low blood pressure; rapid, weak and irregular breathing; lack of energy; and dark urine or decreased urination. If the body is not immediately provided with fluids, prolonged dehydration can lead to kidney failure, changes in blood volume and chemistry, and eventually death.

Unfortunately, children (and even adults) do not always recognize and verbalize the sensation of thirst. Instead, older children let you know when their bodies need fluid by requesting a specific beverage, and the beverage requested is rarely water. Young children are more likely to say things like “More juice;” “Want my baba (or some other name for a bottle or a sipper cup);” or “Milk, please” than a clear “I’m thirsty.” However, some of these specific requests may be for food or simply for comfort.

Knowing how to help a child learn the difference between thirst and hunger, as well as knowing when a child needs fluids, and what to offer a thirsty child can help you make sure children in your care get enough fluids.

It is no wonder that children have a hard time knowing when they are thirsty. After all, many adults do not recognize their own thirst and even if they do “know” they are thirsty, they often ignore the sensation. As adults age, they are even less able to recognize their own thirst.

Most adults assume that babies and young children know when they need fluids. While there are classic signs of hunger in infants and children, there is little research on how young children feel and express thirst. The classic sign of thirst is a dry mouth which is triggered by the brain to induce the intake of fluid and actually is a delayed sign of the need for fluid. But scientists do not know how children recognize “dry mouth” and then signal their need for fluids. Young children may only know that they are uncomfortable.

Therefore, it becomes the caregivers’ responsibility to help children learn the words associated with this sensation, and recognize other body signals that tell them they are thirsty. This is no different from teaching children to put words to other body sensations.

For example, if a child skins her knee, you ask, “Does it hurt?” If a child asks for food, you ask if he is hungry (“Is your tummy making noises?”). And if a child says she does not feel good, you run through the various body parts with her--head, throat, tummy--to determine what might be ailing her. For a child to learn to express thirst, adults have to help them learn the needed words and expressions. Young children might not be able to describe dry mouth explicitly but might express other sensations associated with thirst, such as “sticky tongue.”

So the next time a child tells you that he wants juice or milk, use the opportunity to help him learn to tell the difference between thirst and hunger. Ask the child, “Is your tummy growling or is your tongue sticky?” and teach him how to recognize what need each sensation indicates. A growling tummy means hunger, so offer the child healthful food. A sticky tongue indicates thirst, and water should be offered, because water is the best thirst quencher. Other beverages contain water, but they also contain energy (calories). That is fine when children need more energy, but is not necessary when the body is simply craving fluid.

How Much Fluid?

The specific amount of fluid children need depends on their size, where they live, what they eat, and how active they are. While 6-8 cups of liquid a day are recommended for adults, there is no set amount recommended for young children.

Adults can determine a child’s fluid needs by gently pinching the top of the child’s hand. If the child’s skin feels soft, it is likely that the child is sufficiently hydrated. The skin of the child who does not have enough body fluid (dehydration) will “stick” together when pinched, a clear sign that fluid is needed.

Infants fed breast milk or infant formula (prepared according to the instructions) do not need additional water. Currently, no additional fluids are recommended beyond those required to meet the infant’s growth needs. This is true in all geographical locations and in any kind of weather.

As the baby starts to eat semi-solid foods, additional fluid is still not recommended because most baby foods (homemade or commercially prepared) contain large amounts of water. As children are introduced to foods with less water (such as meats, etc.) and more fiber, their need for additional liquids increases.

What Fluids to Give

Water is the preferred fluid to give to quench thirst. Yet many adults reach instead for juice or milk when children say they are thirsty. Why? The most obvious answer is that most children prefer these fluids to water. They taste sweet and children will drink them. You want to give children what they like and want to make certain they are hydrated. You do not want to waste money by serving things children will not accept. In addition, juice and milk contain nutrients, so are these better? Not necessarily.

Milk and juices are important sources of a variety of nutrients. Children only need six ounces of juice and two cups of milk a day to provide daily needed nutrients such as calcium. This quantity is not nearly enough to meet all of the child’s fluid needs.

However, if more milk or juice is served than necessary, extra energy is added in the form of calories. This increases the likelihood of overweight and obesity, increases your costs, and does not help the child, because any nutrients such as vitamin C, beyond what the body needs, are simply urinated away.

Certain fluids that are always inappropriate for young children include teas of any kind, herbal drinks, energy drinks, and beverages containing caffeine (coffee and colas).

If children are not used to being offered water, they probably will not want to drink it, especially if they know there is juice or milk available. One way to get children to accept water is to serve water when a child asks for fluids. Make it available at all times, even during meals and keep juice and milk to serve as foods.

Madeleine Sigman-Grant, PhD, RD
University of Nevada Cooperative Extension, Las Vegas, NV

Cleveland Clinic, www.clevelandclinic.org, type “dehydration” in the search window

Medline Plus, www.nlm.nih.gov/medlineplus/ency/article/000982.htm

WedMD, http://my.webmd.com/hw/health_guide_atoz/hw86827.asp