Overview
Dehydration occurs when you use or lose more fluid than you take in, and your body doesn't have enough water and other fluids to carry out its normal functions. If you don't replace lost fluids, you will get dehydrated.
Anyone may become dehydrated, but the condition is especially dangerous for young children and older adults.
The most common cause of dehydration in young children is severe diarrhea and vomiting. Older adults naturally have a lower volume of water in their bodies, and may have conditions or take medications that increase the risk of dehydration.
This means that even minor illnesses, such as infections affecting the lungs or bladder, can result in dehydration in older adults.
Dehydration also can occur in any age group if you don't drink enough water during hot weather — especially if you are exercising vigorously.
You can usually reverse mild to moderate dehydration by drinking more fluids, but severe dehydration needs immediate medical treatment.
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Symptoms
Thirst isn't always a reliable early indicator of the body's need for water. Many people, particularly older adults, don't feel thirsty until they're already dehydrated. That's why it's important to increase water intake during hot weather or when you're ill.
The signs and symptoms of dehydration also may differ by age.
Infant or young child
- Dry mouth and tongue
- No tears when crying
- No wet diapers for three hours
- Sunken eyes, cheeks
- Sunken soft spot on top of skull
- Listlessness or irritability
Adult
- Extreme thirst
- Less frequent urination
- Dark-colored urine
- Fatigue
- Dizziness
- Confusion
When to see a doctor
Call your family doctor if you or a loved one:
- Has had diarrhea for 24 hours or more
- Is irritable or disoriented and much sleepier or less active than usual
- Can't keep down fluids
- Has bloody or black stool
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Causes
Sometimes dehydration occurs for simple reasons: You don't drink enough because you're sick or busy, or because you lack access to safe drinking water when you're traveling, hiking or camping.
Other dehydration causes include:
- Diarrhea, 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. 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.
- Excessive sweating. You lose water when you sweat. 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.
- 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, generally because they cause you to urinate more.
Risk factors
Anyone can become dehydrated, but certain people are at greater risk:
- Infants and children. The most likely group to experience severe diarrhea and vomiting, infants and children are 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.
- 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, and this can lead to an increased body temperature and the need for more fluids.
Complications
Dehydration can lead to serious complications, including:
- Heat injury. If you don't drink enough fluids when you're exercising vigorously and perspiring heavily, you may end up with a heat injury, ranging in severity from mild heat cramps to heat exhaustion or potentially life-threatening heatstroke.
- Urinary and kidney problems. Prolonged or repeated bouts of dehydration can cause urinary tract infections, kidney stones and even kidney failure.
- Seizures. Electrolytes — such as potassium and sodium — help carry electrical signals from cell to cell. If your electrolytes are out of balance, the normal electrical messages can become mixed up, which can lead to involuntary muscle contractions and sometimes to a loss of consciousness.
- Low blood volume shock (hypovolemic shock). This is one of the most serious, and sometimes life-threatening, complications of dehydration. It occurs when low blood volume causes a drop in blood pressure and a drop in the amount of oxygen in your body.
Prevention
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.
By Mayo Clinic Staff
Oct. 14, 2021
FAQs
What are 5 causes of dehydration? ›
Dehydration is caused by not drinking enough fluid or by losing more fluid than you take in. Fluid is lost through sweat, tears, vomiting, urine or diarrhoea. The severity of dehydration can depend on a number of factors, such as climate, level of physical activity and diet.
What is the number one cause of dehydration? ›Anyone can become dehydrated if they don't take care of themselves and drink water. However, infants and children, especially when they're sick, are at a higher risk because they may be unable to communicate that they're thirsty. Monitor the amount of fluids your kids take in. Older adults are also at a higher risk.
What happens when your body is very dehydrated? ›Unconsciousness from dehydration can result from low blood pressure or dizziness. When accompanied by other dehydration signs, this could be indicative of severe fluid loss. If you or someone you know is feeling lightheaded or hot due to a high body temperature, they might be on the brink of passing out.
What problems can dehydration cause? ›Symptoms can include thirst, dry mouth, and less urine. Mild dehydration can cause problems with blood pressure, heart rate, and body temperature. Severe dehydration can also cause weakness or confusion. In extreme cases, it can lead to kidney damage, brain damage and even death.
What diseases cause dehydration? ›Many diseases -- such as diabetes, cystic fibrosis, and kidney disease -- increase dehydration risk and the need for fluids. For example, people with uncontrolled diabetes urinate frequently. Some medications can also cause a person to urinate or sweat more than normal.
What is the quickest way to rehydrate? ›- WATER. If you have to ask how to rehydrate, then the answer is a definite no-brainer: drink water. ...
- COFFEE & TEA. ...
- SKIM & LOW FAT MILK. ...
- FRUITS AND VEGETABLES. ...
- ORAL HYDRATION SOLUTIONS.
Water. While it likely comes as no surprise, drinking water is most often the best and cheapest way to stay hydrated and rehydrate. Unlike many other beverages, water contains no added sugars or calories, making it ideal to drink throughout the day or specifically when you need to rehydrate, such as after a workout.
Can you be dehydrated and still pee clear? ›The relationship between urine colour and hydration status
The issue is that, whilst urine colour can definitely be somewhat indicative of hydration status, there's definitely not a simple and linear relationship between actual hydration status and the colour of your pee.
Water is your best bet for everyday hydration, since it is free of sugar, calories, and caffeine. All of your daily food and beverages contribute to your daily fluid needs.
What are the first signs of severe dehydration? ›- feeling thirsty.
- dark yellow, strong-smelling pee.
- peeing less often than usual.
- feeling dizzy or lightheaded.
- feeling tired.
- a dry mouth, lips and tongue.
- sunken eyes.
How long does it take to rehydrate your body? ›
In general, however, it usually takes about two hours for your body to rehydrate fully after drinking a significant amount of water. As for how you should rehydrate, water is the best choice. Sports drinks, such as Gatorade, can be helpful for athletes who need to replenish electrolytes.
What organs are affected by dehydration? ›The skin, muscles, kidneys, brain, and heart can all suffer from the effects of dehydration.
How long can a person go dehydrated? ›How Long Can a Normal Person Survive Without Water. The body requires a lot of water to maintain an internal temperature balance and keep cells alive. In general, a person can survive for about three days without water.
Can you be dehydrated even if you drink a lot of water? ›So, what if you drink loads of water each day but are still feeling thirsty and dehydrated? It can be a sign that something else is going on. Factors like your medication, how much you sweat and if you're sick can affect your levels of hydration.
How does dehydration affect blood pressure? ›When your body is dehydrated, it releases higher amounts of a chemical called vasopressin. Vasopressin helps your kidneys retain water, which can prevent you from losing more water through urination. At the same time, it causes your blood vessels to constrict, which then causes your blood pressure to increase.
Does sleep help dehydration? ›Getting a sufficient amount of high-quality sleep is an important part of preventing dehydration. The body goes through multiple complex processes during sleep that enable recovery for overall health.
What hydrates faster than water? ›Research shows that milk is one of the best beverages for hydration, even better than water or sports drinks. Researchers credit milk's natural electrolytes, carbohydrates, and protein for its effectiveness.
What drink has the best electrolytes? ›- Gatorade & Powerade. Sports drinks like Gatorade and Powerade are electrolyte-rich powerhouses. ...
- Milk. Cow's milk is a bit of an underappreciated superstar when it comes to electrolyte drinks. ...
- Fruit Juices. Fruit Juices are rich in electrolytes. ...
- Coconut Water. ...
- Smoothies. ...
- Tablet-Infused Water.
Is it OK to drink electrolytes every day? You can drink electrolytes every day (or choose to consume a supplement instead). This is especially necessary if you exercise and/or sweat often. Electrolytes will help replace minerals, such as sodium, magnesium, and potassium, that are lost when you sweat or get sick.
What hydrates you faster water or Gatorade? ›While Gatorade can help you stay hydrated, it's best to only drink it when needed. For people who aren't exercising for at least one hour, five days per week, water is the best bet for staying hydrated.
What vitamin helps with hydration? ›
If you're feeling dehydrated or run down, a vitamin C drip could be just the thing you need to feel energetic and well again. If you're concerned about getting an overdose of vitamin C, don't worry. This vitamin is water-soluble, which means any excess beyond what your body needs is excreted with your urine.
Is Gatorade good for hydration? ›Gatorade, because of its electrolyte content, helps to restore the lost electrolytes and keep a person hydrated, during intense activity. It can also replace electrolytes, during times of illness, such as stomach viruses.
What color is your pee when you have kidney failure? ›When kidneys are failing, the increased concentration and accumulation of substances in urine lead to a darker color which may be brown, red or purple. The color change is due to abnormal protein or sugar, high levels of red and white blood cells, and high numbers of tube-shaped particles called cellular casts.
Is it normal to pee every 2 hours? ›Every woman goes on her own schedule, but generally, peeing 6-8 times in 24 hours is considered normal for someone who is healthy, and isn't pregnant. If you're going more often than that, you may be experiencing frequent urination. Frequent urination can happen on its own and isn't always a sign of a health problem.
How many times a day should you pee? ›For most people, the normal number of times to urinate per day is between 6 – 7 in a 24 hour period. Between 4 and 10 times a day can also be normal if that person is healthy and happy with the number of times they visit the toilet.
What do doctors prescribe for dehydration? ›| Drug name | Rating | Rx/OTC |
|---|---|---|
| Expand current row for information about Isolyte S Isolyte S | Rate | Rx |
| Generic name: lvp solution systemic Drug class: intravenous nutritional products For consumers: dosage, side effects For professionals: Prescribing Information | ||
Both are good as oral rehydration solutions, but Pedialyte may be better in cases of diarrhea (since sugar promotes diarrhea and Pediatlyte is lower in sugar). For sports, Gatorade's high sugar content may help fuel athletic performance and duration.
Is Gatorade or liquid IV better for dehydration? ›Is Liquid IV much better than Gatorade? Liquid IV has 3 times the electrolytes and less than half the sugar and calories of Gatorade.
How do you test if you are dehydrated? ›The skin turgor test involves grasping the skin on the lower arm or abdomen between two fingers and then releasing it after a few seconds. Hydrated skin will rapidly return to its normal position, while dehydrated skin will remain in a “tented” position and take much longer to bounce back ( 9 ).
How do you test for severe dehydration? ›Urinalysis. Tests done on your urine can help show whether you're dehydrated and to what degree. They also can check for signs of a bladder infection.
How much water do I need to drink to rehydrate? ›
2. During work or exercise in the heat: • Drink 8-12 ounces of fluid every 15 minutes. Drinking more than 1.5 liters per hour is not recommended and may increase the risk for developing hyponatremia (low sodium).
How long does it take for a glass of water to go through the body? ›After you drink water, it doesn't take long at all for your body to absorb it. Unlike foods, water can be “digested” in as little as 5 minutes. Excess water leaves your body through urination and feces but is also excreted by sweating.
How much water does it take to rehydrate? ›Rehydrating Your Body
It's recommended to drink at least 64 ounces of water every day. You can also receive the water you need from other beverages, fruits, and vegetables. Drinking coffee and tea in moderation can help contribute to hydration. Caffeine, however, can be extremely dehydrating.
- feeling thirsty.
- dark yellow, strong-smelling pee.
- peeing less often than usual.
- feeling dizzy or lightheaded.
- feeling tired.
- a dry mouth, lips and tongue.
- sunken eyes.
So, what if you drink loads of water each day but are still feeling thirsty and dehydrated? It can be a sign that something else is going on. Factors like your medication, how much you sweat and if you're sick can affect your levels of hydration.
Is Gatorade good for dehydration? ›Pedialyte and Gatorade are both designed to prevent or treat dehydration. In fact, thanks to their electrolyte content, they're more effective than water at rehydrating.