There are several causes of dehydration that are important for you to know and take necessary action. Dehydration occurs when a person’s water loss exceed water intake. It can occur as a result of disease or exercise, or environmental issues such as temperature, or lack of available water. When a person loses 3% to 4% of their total water they usually do not experience adverse effects. But once dehydration reaches 5% to 8%, the person may feel dizzy and tired. After 10% of water is lost, the brain and body begin to have difficulty functioning properly and extreme thirst sets in. If dehydration reaches 15% to 25%, it can become fatal.
- Hydration can be achieved through sufficient liquid intake, but food contributes to hydration as well because of its water content. Roughly 20% of a person’s water comes from food. Some foods have very high water content, such as watermelons and cucumbers.
- Eating a lot of salt can result in dehydration.
- Individuals that feel tired all the time might be dehydrated. Dehydration is considered to be the main cause of midday burn-out.
- Once a person feels thirsty, they are already dehydrated. It may take only 1% to 2% dehydration to cause a person to become thirsty.
- Short-term memory, concentration, anxiety levels, irritability and attention span are all negatively affected by dehydration.
- Drinking cold water is believed to help boost one’s metabolism because the body must use energy to heat the cold water up to body temperature.
- Water is lost through normal daily bodily functions such as breathing and urinating. It is also lost through sweat and bowel movements.
- Many other fluids people drink contain caffeine or alcohol, which contributes to water loss.
- An individual that is chronically dehydrated is more likely to develop kidney stones. Individuals with kidney stones who increase water intake can reduce the occurrence of stones in the future.
- Young children and the elderly populations are more susceptible to dehydration.
- As much as 75% of the human body is made up of water, with most being in the body’s cells.
- An individual that is sick, with vomiting or diarrhea, will lose more water than normal and it is important to replace this to avoid becoming even more ill.
The Common Causes of Dehydration
It’s normal to lose water from your body every day by sweating, breathing, peeing, pooping, tears and saliva (spit). Usually you replace the lost liquid by drinking fluids and eating foods that contain water. If you lose too much water or don’t drink and eat enough, you can get dehydrated.
One of the common causes of dehydration is diarrhea and vomiting. Severe acute diarrhea, that is, diarrhea that comes on suddenly and violently can cause a tremendous loss of water and electrolytes in a short amount of time. If you have vomiting along with diarrhea, you lose even more fluids and minerals.
Fever also one of the causes of dehydration and water loss from the body. In general, the higher your fever, the more dehydrated you may become. The problem worsens if you have a fever in addition to diarrhea and vomiting.
If you do vigorous activity and don’t replace fluids as you go along, you can become dehydrated. Hot, humid weather increases the amount you sweat and the amount of fluid you lose.
In some conditions, more water loss can occur through increased urination. This may be due to undiagnosed or uncontrolled diabetes. Certain medications, such as diuretics and some blood pressure medications, also can lead to dehydration because they cause you to urinate more.
Who Are Those Most At Risk?
Anyone can become dehydrated, but certain people are at greater risk:
- Infants and children: The most likely group to experience severe diarrhea and vomiting are infants and children. This makes them especially vulnerable to dehydration. Having a higher surface area to volume area, they also lose a higher proportion of their fluids from a high fever or burns. Young children often can’t tell you that they’re thirsty, nor can they get a drink for themselves. So it’s best mothers give their children water regularly even if they don’t want to drink.
- Older adults: As you age, your body’s fluid reserve becomes smaller. Your ability to conserve water is reduced and your thirst sense becomes less acute. These problems are compounded by chronic illnesses such as diabetes and dementia, and by the use of certain medications. Older adults also may have mobility problems that limit their ability to obtain water for themselves.
- People with chronic illnesses: Having uncontrolled or untreated diabetes puts you at high risk of dehydration. Kidney disease also increases your risk, as do medications that increase urination. Even having a cold or sore throat makes you more susceptible to dehydration because you’re less likely to feel like eating or drinking when you’re sick.
- People who work or exercise outside: When it’s hot and humid, your risk of dehydration and heat illness increases. That’s because when the air is humid, sweat can’t evaporate and cool you as quickly as it normally does. This can lead to an increased body temperature and the need for more fluids.
Symptoms and Signs of Dehydration To Look Out For
- Dry or sticky mouth.
- Not peeing very much.
- Dark yellow pee.
- Dry, cool skin.
- Muscle cramps.
- Not peeing or having very dark yellow pee.
- Very dry skin.
- Feeling dizzy.
- Rapid heartbeat.
- Rapid breathing.
- Sunken eyes.
- Sleepiness, lack of energy, confusion or irritability.
Symptoms for babies and young children
- Dry mouth and tongue.
- No tears when crying.
- Dry diapers for 3 hours.
- Sunken eyes, cheeks, soft spot on the top of the skull.
- Sleepiness, lack of energy, or irritability.
How is Dehydration Diagnosed?
It is important that you visit the hospital or take your child to the hospital if they are losing a lot of water through any of the ways discussed above. Your doctor will try to figure out which of the causes of dehydration is responsible and treat it adequately.
Before beginning any tests, your doctor will go over any symptoms you have to rule out other conditions. After taking your medical history, your doctor will check your vital signs, including your heart rate and blood pressure. Low blood pressure and rapid heart rate can indicate dehydration.
Your doctor may use a blood test to check your level of electrolytes, which can help indicate fluid loss. A blood test can also check your body’s level of creatinine. This helps your doctor determine how well your kidneys are functioning, an indicator of the degree of dehydration.
A urinalysis is an exam that uses a sample of urine to check for the presence of bacteria and electrolyte loss. The color of your urine can also indicate dehydration when combined with other symptoms. Dark urine alone can’t diagnosis dehydration.
Severe dehydration is a medical emergency and needs to be treated immediately. Treatment of severe dehydration includes admitting the patient in the hospital and the use of intravenous infusions to replace lost fluids and electrolytes.
How You Can Prevent Dehydration
To prevent dehydration, drink plenty of fluids and eat foods high in water such as fruits and vegetables. Letting thirst be your guide is an adequate daily guideline for most healthy people. People may need to take in more fluids if they are experiencing conditions such as:
- Vomiting or diarrhea: If your child is vomiting or has diarrhea, start giving extra water or an oral rehydration solution at the first signs of illness. Don’t wait until dehydration occurs.
- Strenuous exercise: In general, it’s best to start hydrating the day before strenuous exercise. Producing lots of clear, dilute urine is a good indication that you’re well-hydrated. During the activity, replenish fluids at regular intervals and continue drinking water or other fluids after you’re finished.
- Hot or cold weather: You need to drink additional water in hot or humid weather to help lower your body temperature and to replace what you lose through sweating. You may also need extra water in cold weather to combat moisture loss from dry air, particularly at higher altitudes
- Illness: Older adults most commonly become dehydrated during minor illnesses such as influenza, bronchitis or bladder infections. Make sure to drink extra fluids when you’re not feeling well.
- Marx JA, et al., eds. Infectious diarrheal disease and dehydration. In: Rosen’s Emergency Medicine: Concepts and Clinical Practice. 8th ed. Philadelphia, Pa.: Saunders Elsevier; 2014.
- Somers MJ. Clinical assessment of hypovolemia (dehydration) in children.
Mayo Clinic Staff. (2018). Dehydration.
Mayo Clinic Staff. (2017). Water: How much should you drink every day?