Dehydration is the absence of enough water in your body. The best way to beat it is to drink before you get thirsty. If you’re thirsty, you’re already mildly dehydrated, and that can cause signs of dehydration like headache, fatigue, dizziness and more. Dehydration can contribute to life-threatening illnesses like heatstroke.


What is dehydration?

It’s a warm summer day, and you’re feeling parched. Make sure you reach for a tall glass of water. You’re already beginning to feel the signs of dehydration.

Dehydration is a condition in which you lose so much body fluid that your body can’t function normally. It occurs when you lose more fluids than you take in. Dehydration may happen on a particularly hot day if you sweat a lot, or if you’re sick with fever, diarrhea or vomiting. It can also occur if don’t drink enough water, or if you’re taking a medication that increases your pee (urine) output.

When you aren’t properly hydrated, your body’s natural response is thirst. You should respond to thirst right away by drinking fluids — preferably water. You can usually treat mild dehydration by drinking more fluids. But dehydration isn’t always easy to spot. It can be found in the aging parent who forgets to drink water or the fussy baby who can’t tell you they’re thirsty. Make sure to keep your loved ones hydrated. If you or a loved one has a moderate to severe case of dehydration, you may need to go to the hospital to get IV fluids. Left untreated, severe dehydration can be fatal.

What does water do for your body?

Up to 78% of your body is made of water. Your brain is made up of 73% water, and so is your heart. Your bones are 31% water, your muscles and kidneys are 79%, and your skin is 64%. A whopping 83% of water makes up your lungs.

Water helps:

  • Aid digestion and get rid of waste.
  • Your joints work. Water lubricates them.
  • Make saliva (which you need to eat).
  • Balance your body’s chemicals. Your brain needs it to create hormones and neurotransmitters.
  • Deliver oxygen all over your body.
  • Cushion your bones.
  • Regulate your body temperature.
  • Act as a shock absorber for your brain, your spinal cord and, if you’re pregnant, the fetus.

Water is important to your body, especially in warm weather. It keeps your body from overheating. When you exercise, your muscles generate heat. To keep from burning up, your body needs to get rid of that heat. The main way your body discards heat in warm weather is through sweat. As sweat evaporates, it cools the tissues beneath. Lots of sweating reduces your body’s water level, and this loss of fluid affects normal bodily functions.


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Symptoms and Causes

What are the symptoms of dehydration?

If you suspect that you or your child is severely dehydrated, seek immediate medical attention. Signs of dehydration in kids include:

  • Dry tongue and dry lips.
  • No tears when crying.
  • Fewer than six wet diapers per day (for infants), and no wet diapers or urination for eight hours (in toddlers).
  • Sunken soft spot on your infant’s head.
  • Sunken eyes.
  • Dry, wrinkled skin.
  • Deep, rapid breathing.
  • Cool, blotchy hands and feet.

Dehydration symptoms in adults may include:

Can dehydration cause fever?

No, dehydration doesn’t typically lead to fever. But many diseases and disorders that cause fever can also cause dehydration.

Does dehydration cause high blood pressure?

Dehydration can actually make your blood pressure drop to dangerously low levels. When this happens, your body goes to work to try to correct it. But in doing so, your body can overcorrect and make your blood pressure skyrocket.

Can dehydration cause diarrhea?

No, but diarrhea can cause dehydration. Severe diarrhea causes a loss of fluids in your body.

Can dehydration cause nausea?

Yes, dehydration can lead to disorientation and dehydration headaches. One of the symptoms of these headaches is nausea and vomiting.

What causes dehydration?

Dehydration happens when you don’t drink enough water, or when you lose water quickly through, for example, sweating, vomiting and/or diarrhea. Certain medications like diuretics (water pills) can result in increased urination and dehydration.

What are the risk factors for dehydration?

Anyone can become dehydrated if they don’t drink enough water. But infants and children are at a higher risk because they may be unable to communicate that they’re thirsty. This is especially important when they’re sick. So, make sure to monitor the amount of fluids your child takes in.

Adults ages 65 and older are also at a higher risk. They don’t carry as much water in their bodies and they can’t tell as easily when they’re thirsty. If you’re a caregiver, especially for someone with memory problems, offer them drinks frequently. Even if they’re enduring an uncomfortable infection like a UTI (urinary tract infection), they still need to consume liquids.


What are the complications of dehydration?

If you or your child has symptoms of severe dehydration, get medical care right away. Severe dehydration can lead to serious complications, including:

Diagnosis and Tests

How is dehydration diagnosed?

If you feel thirsty, you’re already dehydrated. That’s the easiest way to tell that you need more fluids. If you see your healthcare provider for possible dehydration, they may diagnose the condition based on your symptoms and a physical exam. Laboratory tests can also diagnose dehydration. These tests may include:

  • Blood tests to check your electrolyte levels and kidney function.
  • Urine tests to check for possible causes of dehydration.

What are the levels of dehydration?

Healthcare providers categorize dehydration as:

  • Mild: You just have to take in more fluids orally (by mouth). Drink water, but replace fluids with a drink that contains electrolytes if you experience significant sweating or fluid loss from vomiting and diarrhea. You should feel better after five or 10 minutes.
  • Moderate: Moderate dehydration requires an IV (hydration through your vein). You’ll get this in an urgent care, emergency room or hospital.
  • Severe: See a healthcare provider if your symptoms of dehydration are severe. Call 911, your local emergency services number or go to an emergency room.

If you’re seeing a healthcare provider, they’ll figure out what level you’re at to assign you treatment.


Management and Treatment

What is the fastest way to cure dehydration?

Drink water. You could also try increasing your hydration with oral rehydration sachets — powders you mix in with your water.

How can I help my dehydrated child get better at home?

  • Carefully follow your child’s provider’s instructions for feeding.
  • Don’t give children younger than age 2 over-the-counter (OTC) medicine for diarrhea, unless instructed by their provider.
  • Encourage your child to drink fluids that are unsweetened (sugary sodas, juices and flavored gelatin can irritate diarrhea).
  • Continue to breastfeed (chestfeed) infants normally.
  • Electrolyte solutions may be helpful when given as recommended by their provider.
  • Slowly increase the amount of fluid and food you give your child.
  • Give your child acetaminophen (Tylenol®) for fever. Don’t give your child aspirin.
  • Allow your child plenty of rest.
  • Watch for signs of dehydration that get worse or come back.

Hospital treatment of dehydration

You can usually treat dehydration at home, but severe cases may require hospitalization. Hospital care may include:

  • Fluids given intravenously (IV), or through your vein.
  • Monitoring of electrolyte imbalance.
  • Acetaminophen for fever.
  • Rest.


Can dehydration be prevented?

Yes, you can prevent dehydration by keeping track of how much fluid you drink. Drink water throughout the day, including at meals. Avoid soda, alcohol and caffeinated drinks. One way to make sure you’re properly hydrated is to check your pee. If it’s clear, pale or straw-colored, it’s OK. If it’s darker than that, keep drinking.

To avoid dehydration, active people — people playing a sport or exercising — should drink at least 16 to 20 ounces (oz.) of fluids one to two hours before an outdoor activity. After that, you should consume six to 12 ounces of fluid every 10 to 15 minutes when you’re outside. When you’re finished with the activity, you should drink more. To replace what you’ve lost, drink at least another 16 to 24 ounces.

How much water do I need to drink?

Exactly how much water you need depends on your weight, age, level of activity, the climate of your environment and other factors. People with diabetes, heart disease, cystic fibrosis and other conditions may need to be cautious. The amount of water you need can also depend on the climate and what clothes you’re wearing. Although the standard advice is eight glasses of water per day, talk to your healthcare provider to confirm the right amount for you.

Which beverages hydrate the body, and which dehydrate?

Some beverages are better than others at preventing dehydration. Water is all you need if you’re planning to be active in a low- or moderate-intensity activity, such as walking for only an hour or less. If you plan to exercise longer than that, or if you anticipate being out in the sun for more than a few hours, you may want to hydrate with some kind of sports drink. These replace not only fluid but also electrolytes like sodium and potassium, which are lost through sweating. Too much or too little sodium and potassium in your body can cause trouble. Muscle cramping may be due to a deficiency of electrolytes.

Healthcare providers don’t recommend beverages containing alcohol or caffeine for optimal hydration. These fluids tend to pull water from your body and promote dehydration. Fruit juice and fruit drinks may have too many carbohydrates and too little sodium, and they may upset your stomach.

How do I get myself and my loved ones to drink more water?

  • Carry a water bottle with you. Keep it filled.
  • Choose water instead of sugary drinks, including at meals.
  • Add flavor. A wedge of lime or lemon might make it tastier. You can also try some flavored drink mixes, but watch out for the sugar.
  • Eat foods that are high in water content. Many soups, fruits and vegetables meet this description.
  • If you don’t like drinking a lot of water at once, try smaller doses spread out throughout the day.

Outlook / Prognosis

What is the outlook (prognosis) for dehydration?

By drinking more fluids, you can typically treat any bout of mild hydration. More moderate to severe cases of dehydration may require hospitalization for treatment with IV fluids. Left untreated, severe dehydration can lead to serious complications, including electrolyte imbalances, organ failure and death.

How long does dehydration last?

If you resolve the issue that caused dehydration and you get the correct amount of fluids, mild to moderate dehydration should go away in less than a day. You should seek treatment for severe dehydration in a hospital. With appropriate treatment, dehydration should resolve within two to three days.

Living With

What can I drink for dehydration?

Always drink water immediately if you feel thirsty. Remember — if you feel thirsty, you’re already dehydrated. You may see the signs of dehydration improve in as little as five to 10 minutes.

When should you worry about dehydration in a baby?

Call your baby’s provider if your baby:

  • Has any signs of dehydration.
  • Has increased vomiting or diarrhea.
  • Has no wet diapers or urination within eight hours.
  • Is lethargic (sleeping more and less playful).

When should I go to the ER?

If you think your symptoms of dehydration are severe, don’t hesitate to seek help. Dehydration can contribute to kidney stones, kidney failure and heatstroke — all life-threatening illnesses. Call 911, your local emergency services number or go to the emergency room right away if you have symptoms of severe dehydration or heatstroke:

  • A fever of 103 degrees Fahrenheit (39.4 degrees Celsius) or higher.
  • Muscle twitching.
  • Red, hot and dry skin.
  • Nausea.
  • Rapid pulse.
  • Seizures.
  • Lack of sweating.
  • Confusion, altered mental state and/or slurred speech.
  • Dizziness.
  • Fainting or loss of consciousness.
  • Hallucinations.

What questions should I ask my healthcare provider?

Questions you may want to ask your healthcare provider include:

  • What caused me to become dehydrated?
  • How can I prevent getting dehydrated in the future?
  • Do I need to change my medications when I’m dehydrated?
  • I don’t like water. Can I drink something else to stay hydrated?
  • Should I give my child medication? If so, for how long and at what times of the day?
  • When will my child start to feel better?
  • Will I need to bring my child back for a follow-up visit?
  • Are there certain foods or liquids my child should have or avoid?
  • Which symptoms should I report to you/your office?

A note from Cleveland Clinic

Dehydration is a lack of sufficient water in your body. It can occur for many different reasons and it can be dangerous if left untreated. Remember — if you feel thirsty, you’re already dehydrated. Always drink water immediately if you feel thirsty. You may see the symptoms of dehydration improve in as little as five to 10 minutes. The amount of water needed on a daily basis depends on many factors, so it’s best to check in with your healthcare provider to determine exactly how much will keep you healthy.

Medically Reviewed

Last reviewed on 06/05/2023.

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