Dehydration (in children, the elderly): see what it is and symptoms


What is dehydration?

Dehydration is the state in which the body finds itself when it lacks not only water, but also body fluids and mineral salts in the body. It is an especially dangerous condition for children and the elderly. Without fluids and minerals, the body does not function properly and the organs can fail.


There are three distinct types of dehydration. In all of them, there is a lack of liquid and sodium, but the difference is the proportion of each fault.

Isotonic dehydration

Children are the main victims of this type of dehydration, but even in adults, it is the most common type of the disease. It happens when the body loses water and sodium in the same proportion, usually through vomiting and diarrhea .

Hypertonic dehydration

This type of dehydration happens when the loss of water  is greater than that of sodium. Especially common in diabetics, it can be caused by high and prolonged fevers, intense sweating and low water intake. Hypertonic dehydration represents 10 to 20% of cases of childhood dehydration.

Hypotonic dehydration

Caused by a  greater loss of sodium than water, hypotonic dehydration is uncommon in adults and the elderly, but 10 to 15% of children who become dehydrated through diarrhea are affected by this type.


The body loses water over the course of a day and needs to replenish it to keep the cells functioning. This loss occurs through speech, breathing, urine, feces, sweat, tears and several other means.

Mineral salts such as sodium and potassium may be diluted in this lost water and they also need to be replaced. Several situations can cause the loss of water and sodium in a person’s body and, if he is prevented from replacing these substances, dehydration sets in.

Lack of water management

The elderly and children are the main victims of this cause, as many need help to hydrate themselves or may even forget to drink water. If a long time goes by without water, the loss during the day through urine, sweat and even simple speech, can lead to dehydration.

Excessive sweat

Sweat eliminates a lot of water to cool the body when it is hot due to temperature or exercise. It is important to replace this water to avoid dehydration. In sweat, sodium is also lost and must be replaced.


Most common cause of dehydration, severe diarrhea causes huge losses of fluid and minerals in a short period of time. People often don’t remember to hydrate themselves soon after or during a bout of diarrhea, which can lead to dehydration.


As with diarrhea, fluids and minerals are lost quickly during vomiting. Children can also be affected more easily than adults by these two causes of dehydration because they are unable to get up and fetch a glass of water all the time.


Fevers cause loss of fluid due to excessive heat in the body, which leads to sweating. If this liquid is not replaced, dehydration can happen.

Frequent urination

Several situations can lead to more frequent urination. The urine is composed mainly of water, and each time we urinate, we lose a large amount of the liquid. The frequency can be increased by conditions such as diabetes , for example, and there is a risk of dehydration if there is no fluid replacement.


Diuretics are substances that make a person urinate more. Some medications have this effect and therefore must be accompanied by plenty of water.


Alcohol is a diuretic substance. It causes the body to eliminate water through the urine, which can lead to dehydration. In addition, it also steals nutrients that are eliminated by the body, so it can cause three different types of dehydration.


Like alcohol, coffee is a diuretic. The water present in it would be enough to keep the person hydrated, but exaggerating the intake of coffee can cause a greater elimination of water than the amount ingested.

Groups of risk

Everyone can suffer from dehydration, but some groups have a little more ease. Are they.


Children are one of the biggest risk groups as they may forget to hydrate, and, depending on their age, they may not have the ability to do so. Children are also more prone to diarrhea.

In addition, the proportion of water in a child’s body is greater than that of an adult, so smaller losses may be more significant for them.


Elderly people may forget to drink water or have a debilitating illness that prevents them from doing this on their own. They also have a greater loss of fluid than a person at other stages of life, so they need to replace more fluids. Like children, they are also more prone to diarrhea.


People with diabetes have a high level of glucose in their blood. The kidneys try to eliminate this excess glucose through the urine and therefore, there is a greater loss of water in this way.

Excessive glucose plus a lack of water can cause hypertonic dehydration. It is important to remember to drink water.

Immunodeficiency sufferers

Immunodeficiencies facilitate infections. The most common cause for diarrhea is infections in the gastrointestinal system and a serious consequence of this is dehydration through the stool, since during diarrhea, the stool is composed of up to 90% water.

Endurance athletes

Long runs, climbing, marathons, triathlons and any endurance activity are a huge effort for the body, which uses a lot of water. It is important for the athlete to stay hydrated during the races to avoid dehydration, which can be severe when ignored in long races.

Risk factors

There are also some factors that can contribute to the possibility of dehydration:


When the temperature is low, we feel less thirsty and hydrate less, but we still lose water through urine, breathing and other means. Hydrating yourself, even in the cold, is very important to avoid dehydration.

High altitudes

The mountain climate is usually quite dry and cold. The temperature can mask the thirst and the dryness of the air increases the amount of water lost by breathing.

In addition, at altitudes above 6000 meters above sea level, atmospheric pressure leaves the oxygen concentration in the air low.

Because of this, the body goes into hyperventilation, making the inhalation faster and deeper, further increasing the loss of water to dry air.

Work or exercise in hot, humid weather

Too humid environments can prevent sweat from evaporating. As it is the evaporation that cools the body, it remains hot and its more, losing more water. Rehydration is extremely important in these environments.


Dehydration can be divided into three different degrees of severity and its symptoms and treatments vary between each degree. Are they:

Mild dehydration

Characterized by a loss of between 1 and 3% of body weight due to lack of hydration, the symptoms of mild dehydration are:


Feeling thirsty is the first sign of dehydration. It is a symptom that only appears when the body starts to lack water, so the ideal is to drink water before  feeling thirsty.


Lack of water in the body is also lack of water in the brain. The headache arises when mild dehydration sets in, and when it is caused by dehydration, it can be resolved with drinking water. Some people have migraines triggered by a lack of water.


With a lack of water, dizziness can occur .


Tiredness is also a symptom of dehydration.


Sodium and potassium are essential mineral salts for the mechanism of muscle contraction. In the absence of any of them, which can happen during dehydration, contraction is affected and cramps can happen.

Dark urine

The urine is composed mainly of water. If it is dark, it means that the concentration of other components is high in it. Less water in the body means less water in the urine.

Lower frequency of urination

There may be less desire to go to the bathroom, a sign that the body is looking to save water.

Bad breath

Due to the lack of water, the body can produce less saliva, which in addition to leaving the mouth dry, allows a greater proliferation of bacteria in the mouth, leading to bad breath .

Food cravings

You may feel hungry, specifically for sweets, because due to lack of water, glycogen transport in the body is impaired. Thus, the body asks for more glycogen, found in large quantities in sweets.

Moderate dehydration

In moderate dehydration, the symptoms of the mild version of the disease intensify, in addition to new ones appearing. Are they:

Sunken eyes

The eyes can be sunken (sunken) with the lack of water in the body.

Increased body temperature

With the lack of water, the body stops sweating to save liquid. This can cause an increase in body temperature, since sweat is the body’s way of cooling.

Dry mouth and eyes

The mouth and eyes are dry during moderate dehydration.


Increased heart rate can happen if there is a lack of water in the patient’s body. The lack of fluid in the body means that there is less blood in it, so the heart needs to beat more to bring blood to all organs.

Weight decrease

The human body is composed mainly of water. Dehydration can be measured by the amount of weight lost in water.

Dry skin

30% of your skin is made up of water. If there is a lack of it, the skin becomes dry and loses elasticity.

It is possible to check the state of dryness by pulling the skin from the back of the hand and checking if it takes time for it to return to normal. At optimal hydration levels, the skin should return to its place almost instantly. If she takes some time to do this, it’s good to hydrate.


Feeling soft in the body is a symptom of a lack of water in the body.

Sinking of the soft spot in babies

Due to the decrease in the amount of water in the brain, the soft spot in babies can get sunk.

Severe or severe dehydration

All previous symptoms are exacerbated in severe dehydration. In addition, the following symptoms appear:

Lack of tears

There may be crying, but there are no tears. It is an easy symptom to see in babies, who cry because of extreme thirst.


If the water levels are extremely low, the kidneys can stop producing urine altogether. Thus, the person does not urinate.

If there is urination, the color of the liquid is extremely dark and has a strong odor, due to the concentration of substances that are not water, such as urea.

Lack of sweat

Sweat, like urine, is no longer produced to save water.

Rapid breathing

Breathing may accelerate if the person is severely dehydrated.

Mental confusion

With a lack of water in the brain, there can be mental confusion. The person may not know where he is, be irritated, and have delusions.

Drop in blood pressure

Due to lack of fluid in the body, blood pressure drops. This can lead to dizziness, fainting and nausea.


Elevated body temperature, without the sweat for temperature control, can lead to seizures .


Severe dehydration can lead a person to a coma.

Multiple organ failure

Without water, the body is unable to function. Dehydration can cause the organs to fail, leading to death.

How is dehydration diagnosed?

The clinical examination, carried out by the general practitioner, is enough to identify dehydration. He will look for symptoms such as dry mouth and eyes, skin elasticity and heart rate, in addition to listening to what the patient has to say about what he feels and the amount of fluid ingested.

However, some tests can be done to find out the exact degree and cause of the lack of water in the body:

Blood test

Through blood tests, it is possible to check the amount of mineral salts present in the body, as well as glucose and indicators of how the kidneys are working. This can indicate the degree of dehydration, as well as the cause.

blood count may be indicated, seeking to identify possible infections that may be causing dehydration.

Urine analysis

Examining the color, clarity and density of urine, in addition to the substances present in it, can indicate the degree to which dehydration is, in addition to possible causes. If there is an increase in glucose in the urine, for example, this may be indicative of diabetes.

Is dehydration curable?

Yes, dehydration can be cured. In mild and moderate cases, a healthy adult can easily heal from dehydration by drinking a glass or two of water slowly. Severe dehydration needs medical attention, but it is also treatable.

What is the treatment?

Dehydration treatments vary depending on her degree and the patient’s age, but always consist of replenishing the body’s water and mineral salts.

Mild and moderate dehydration

This type of dehydration can be treated at home. In the first six months of life, breast milk is ideal for dealing with dehydration. It has all the mineral and liquid salts that your child needs.

Regardless of age, children, adults and the elderly should drink water in small sips. If there is a lack of salts or sugar, eating some candy and something salty by the water is recommended.

It is important to remember that children have more water in their bodies than adults. Therefore, a hypotonic dehydration in  them is especially dangerous, since the mineral salts in your body can be very diluted and giving pure water to them can dilute them even more. The ideal is to give fruit pulp and juices.

Homemade serum

Very effective against mild and moderate dehydration, homemade serum can also be ingested at any age and replenishes fluids and minerals. The recipe is as follows:

  • 1 liter of previously boiled or filtered water (remember not to drink the warm water);
  • 1 shallow teaspoon of salt;
  • 2 shallow tablespoons of sugar.

Mix well and drink slowly, sipping. It is not necessary to drink everything, but quenching thirst is recommended. This mixture should be enough to make all the necessary replacement.

Severe dehydration

Severe dehydration may need immediate medical attention, as home-made serum and drinking water do not hydrate the body fast enough.

There is also the possibility that it may be impracticable due to the symptoms of the condition, which can include seizures, mental confusion, delusions and coma. If possible, homemade oral serum is a good option, but especially for children and the elderly, hospitalization may be necessary.

Fluids can be replaced intravenously , which restores the body’s mineral salts and water quickly. The causes of dehydration, then, must be found and treated.

Drugs for dehydration

There are no drugs for dehydration, there are solutions for rehydration, which help the person to recover their minerals and liquids in a faster and more balanced way.

The solutions can be sold in concentrates (which must be mixed with water) and ready-made, which can be drunk straight from the box. Some examples are:

  • Hidrafix ;
  • Aquaben ;
  • Rehidrat ;
  • Sindrat .


NEVER  self-medicate or stop using a medication without first consulting a doctor. Only he will be able to tell which medication, dosage and duration of treatment is the most suitable for his specific case. The information contained in this website is only intended to inform, not in any way intended to replace the guidance of a specialist or serve as a recommendation for any type of treatment. Always follow the instructions on the package insert and, if symptoms persist, seek medical or pharmaceutical advice.

Homemade tips

Homemade serum, already mentioned, is one of the options you can do at home to rehydrate yourself and prevent a case of mild or moderate dehydration from becoming serious. In addition to it, there are other ways to recover fluids and salts from the body:

Fruits and vegetables

Various fruits and vegetables are great sources of water and mineral salts and are exceptional for the recovery of hydration. Highlight for coconut water, which has several electrolytes.

In addition, watermelon , melon and strawberry are fruits with plenty of water that can help, and cucumber is a vegetable with a lot of liquid. Juices made from these ingredients can recover a patient from mild or moderate dehydration.


Despite not being rich in water, bananas have many minerals. In cases of dehydration due to lack of salts (hypotonic dehydration), it can be a great ally for recovery.

Barley tea

Barley can help restore the body’s hydration.


When isolated, dehydration is usually easy to treat and perfectly curable. Patients do not usually have sequelae and can live life normally after healing, remembering to hydrate themselves whenever possible.


The treatment of dehydration is easy, but if it is not applied quickly, the severe version of the condition can lead to serious complications:

Brain edema

If rehydration is not performed properly, brain cells may swell and rupture. In addition, the lack of fluid in the brain can create sequelae.

Hypovolemic shock

The low amount of blood can cause a shock to the patient. During this state, the heart is unable to pump enough blood to the entire body due to its lack. There is a great risk to life and it is a medical emergency.


Due to a lack of mineral salts, the brain’s electrical communication can be affected and cause seizures.


Lack of fluid can lead to organ failure, coma and death.

How to prevent dehydration?

There are ways to prevent dehydration. Are they:

Avoid being in the sun in the hottest hours

The most dangerous times are between 10am and 3pm. At these times, the sun is the highest and hottest in the sky, increasing the temperature and loss of water.

Drink a lot of water

Even when you’re not thirsty, drink water. It is recommended to drink around two liters of water per day. This ensures that your body is well hydrated.

Be careful not to drink too much water, as this can unbalance the minerals in your body, leading to hyponatremia, but avoid reaching the state of feeling thirsty.

Isotonic drinks

Isotonic drinks were created to replace electrolytes and liquids lost during physical exercises, so they are very efficient in rehydrating the body. These drinks can be used to prevent dehydration and can be taken before, during or after exercise.

Coconut Water

The coconut palm fruit has a water rich in electrolytes and is one of the most efficient natural moisturizers, highly recommended to avoid dehydration.

Have water always available

Having water close by is always good. A bottle for when you leave the house can be recommended, in addition to moments of exercise and physical work.

Avoid alcohol, especially on very hot days

Alcohol is an efficient diuretic, so it can easily dehydrate you. On very hot days, it is good to avoid drinking, or at least try to remember to drink plenty of water together.

Take care of children and the elderly

Children and the elderly are the main victims of dehydration and may not be able or remember to hydrate. Remember to take care of them and always make water available.

Hydrate when sick

Especially when you have diarrhea or vomiting, which causes loss of fluid, remember to drink plenty of water to replace everything that is lost.

Dehydration is easy to control, but extremely dangerous, especially for the elderly and children. Remember to always stay hydrated and keep water close at hand.

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