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.
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.
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 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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If you suspect that you or your child is severely dehydrated, seek immediate medical attention. Signs of dehydration in kids include:
Dehydration symptoms in adults may include:
No, dehydration doesn’t typically lead to fever. But many diseases and disorders that cause fever can also cause dehydration.
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.
No, but diarrhea can cause dehydration. Severe diarrhea causes a loss of fluids in your body.
Yes, dehydration can lead to disorientation and dehydration headaches. One of the symptoms of these headaches is nausea and vomiting.
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.
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.
If you or your child has symptoms of severe dehydration, get medical care right away. Severe dehydration can lead to serious complications, including:
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:
Healthcare providers categorize dehydration as:
If you’re seeing a healthcare provider, they’ll figure out what level you’re at to assign you treatment.
Drink water. You could also try increasing your hydration with oral rehydration sachets — powders you mix in with your water.
You can usually treat dehydration at home, but severe cases may require hospitalization. Hospital care may include:
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.
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.
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.
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.
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.
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.
Call your baby’s provider if your baby:
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:
Questions you may want to ask your healthcare provider include:
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.
Last reviewed by a Cleveland Clinic medical professional on 06/05/2023.
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