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an active woman drinking water to prevent dehydration

How to Recognize the Warning Signs of Dehydration

How to Tell if You Are Dehydrated

Water is vital to life on earth, and humans are no exception. We may not realize it, but our bodies are composed mainly of water.

Over 60% of an adult body consists of water. Although we may think our lungs contain more air than anything else, our lungs are 83% water. Our most vital organs, the brain and heart, are 73% water. Even our bones, which we consider strong and solid, are made up of 31% water.

Why the Human Body Needs Water


Humans are built up of cells. Within those cells are spaces mainly occupied by water. The water within our bodies functions as a way to transport nutrients, electrical currents, electrolytes and chemicals. The water allows our body to work efficiently.

When there is water loss in our bodies, our organs can begin to fail. The function of water in our bodies is essential to our health.

  • Water flushes out toxins and waste from our bodies through the kidneys and liver.
  • Water lubricates joints, aids our range of motion and cushions against shocks.
  • Water balances brain activity and boosts brain function.
  • Water enables the lungs to work efficiently.
  • Water transports oxygen, electrolytes and nutrients throughout the body and into cells.
  • Water keeps mucous membranes and tissues in the eyes, nose and mouth moist.
  • Water regulates your body temperature, keeping you from overheating.

Because the body relies so heavily on water, it can't function well without it. Without enough water, our body becomes dehydrated and starts to shut down. This is why it's vital to understand how to tell if you're dehydrated.

Causes of Dehydration

Dehydration occurs when the body loses too much water. Unfortunately, we can quickly become dehydrated without knowing it.

Dehydration occurs when your body loses more water than it's taking in. You may become dehydrated if you experience the following:

  • Remain in a hot environment.
  • Sweat too much due to exercise, environmental conditions or illness.
  • Have a high or prolonged fever.
  • Lose fluids through diarrhea or vomiting.
  • Loss of a large volume of blood.
  • Urinate too much because of a medical condition or medication.
  • Illness such as a cold or flu.

Signs and Symptoms of Dehydration

Dehydration may look different in children compared to adults. Because children, especially infants, have a higher water composition than adults do, they tend to become dehydrated much more quickly. Also, infants and toddlers are unable to clearly express their needs, so adults must understand what dehydration looks like in a young child.

In Children

  • Irritability
  • Sunken eyes
  • High fever
  • Unusually fatigued or sleepy
  • No urination for three hours or more
  • Dry tongue
  • Dry mouth
  • Crying, but with no tears

In Adults

  • Thirst
  • Fatigue
  • Dizziness
  • Dry tongue
  • Dry mouth
  • Dark-colored urine
  • Less sweat and less urine than is typical
  • Dry skin

Sometimes, we can't tell when we're using up all our fluids. For instance, we may not feel sweat when we exert ourselves in cold weather. So, although it may not seem like we're losing fluids, we can still become dehydrated.

It's essential to remain hydrated, even if you're not experiencing any signs and symptoms of dehydration.

What to Do if You Think You’re Dehydrated

Now that you know how to tell if you are dehydrated, what should you do about it? Fortunately, in most cases, dehydration can be alleviated by replacing fluids and electrolytes, either by drinking fluids or through intravenous administration in a hospital.

It's crucial to not only replace the water in your body but also the electrolytes within the water you've lost. This replacement is especially crucial in infants and young children who depend on the electrolytes in fluids to remain healthy.

For Children

When children experience vomiting or diarrhea, they can become dehydrated fairly quickly. According to the Mayo Clinic, infants and children can re-hydrate using over-the-counter solutions meant especially for children. These contain specific electrolytes formulated for a child’s body. To administer, follow the directions on the solutions or call your healthcare provider.

For Adults

Adults who experience dehydration can drink cool water or sports drinks. Drinks like coffee, soft-drinks, or fruit juices — though they contain water — can worsen digestive illnesses or create further electrolyte imbalances. Water and sports drinks are better choices when it comes to treating dehydration.

How to Recognize Severe Dehydration

In both infants and adults, extreme dehydration can be life-threatening. If the following symptoms are present, seek immediate medical attention:

  • Fainting
  • Fast heartbeat
  • Breathing quickly
  • Shock
  • Lack of urination
  • Confusion

How Much Water Do You Need?

Harvard Health advises healthy adults to drink four to six cups of water a day. However, for some people, too much water can be an issue. Adults who take medications for pain or take antidepressants may need to avoid drinking too much water. For these people, and others with severe health conditions, obtain advice from a physician regarding appropriate daily water intake.

Guidelines for Children

Children have much more varied requirements for water, depending on their age.

For infants aged five months and under, water is not recommended.

At an age of six months, water can be offered up to one cup a day.

Children aged 12 to 24 months can drink one to four cups of water a day, and children 24 months to age five can drink one to five cups a day.

It's essential to remember that children also receive a majority of their fluids through milk and other drinks.

Don't Take Water for Granted

During hot days, drinking water and staying cool should be a priority. Take time out of your fun in the sun to drink some water and rehydrate. Your body will thank you for it.

And remember, these are general guidelines for how to tell if you are dehydrated. If you are not sure, or suspect something is wrong, don't hesitate to seek professional medical advice.

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