Dehydration: Causes & Symptoms (2023)

Overview

What is dehydration?

Warm weather brings with it thoughts of cool ocean breezes, napping in a hammock and sipping a tall glass of lemonade. Now hold on to the mental image of that lemonade because summer is also a time to be wary of dehydration: the lack of sufficient water in your body, specifically in your cells and blood vessels. Even losing a little bit, as little as 1.5% of your body’s water, can cause symptoms. Those symptoms can be as simple as a slight headache, or the dehydration could contribute to a life-threatening illness like heatstroke (hyperthermia).

Your body’s natural response to inadequate hydration is thirst. You should respond to thirst right away by drinking fluids – preferably water. Drink enough water to prevent yourself from feeling thirsty! Water has zero calories!

What does water do for your body?

Between about 55% to about 78% of your body is made of water. Newborn babies are about 78% water, a year-old baby is 65%, adult men are about 60% and adult women are about 55%. Your brain is made up of 73% water, and so is your heart. Your bones are 31% water, 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.
• Work your joints. 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, your 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 the body discards heat in warm weather is through sweat. As sweat evaporates, it cools the tissues beneath. Lots of sweating reduces the body's water level, and this loss of fluid affects normal bodily functions. Drink water!

Are hypovolemia and dehydration the same?

No, these terms do not mean the same thing. Hypovolemia defines many conditions where extracellular fluid volume is reduced. Dehydration can be one of several causes of hypovolemia, but it is not the same thing as it.

Are dehydration and hypernatremia the same?

No. Again, dehydration can be a cause of hypernatremia, but it is not the same thing.

Possible Causes

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 such as diuretics (water pills) can result in increased urination and dehydration.

Who’s at risk of becoming dehydrated?

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. Their body’s fluid reserves shrink and their body’s ability to tell them they’re thirsty doesn’t work as effectively. This means 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 caretaker of an elderly individual, especially one who may have 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 signs of dehydration? What does dehydration feel like?

If you suspect that you or someone else is severely dehydrated, seek immediate medical attention.

Signs of dehydration include:

• Headache, delirium, confusion.
• Tiredness (fatigue).
• Dizziness, weakness, light-headedness.
• Dry mouth and/or a dry cough.
• High heart rate but low blood pressure.
• Loss of appetite but maybe craving sugar.
• Flushed (red) skin. Swollen feet. Muscle cramps.
• Heat intolerance, or chills.
• Constipation.
• Dark-colored pee (urine). Your pee should be a pale clear color.

The best way to beat dehydration is to drink before you get thirsty. If you wait until after you're thirsty, you're already dehydrated.

In what other ways does dehydration affect me?

Dehydration does more than you might expect. If affects you not only physically (note the signs stated above), but mentally and emotionally as well. If you’re dehydrated, you may feel:

Mental affects:

• Confused.
• Like you can’t remember.

Emotional affects:

• Cranky.
• Anxious.

Note that these symptoms may be worse in someone who has dementia.

How does dehydration affect the brain?

Severe hydration shrinks the blood vessels in the brain. When there aren’t high enough fluid levels in your brain, that affects your memory and coordination.

How does dehydration affect the heart? Can dehydration cause high blood pressure?

Your heart has to work harder when there’s less water in your blood.

How does dehydration affect the kidneys?

The average person urinates (pees) about six or seven times a day. If you’re dehydrated, you may urinate less. This is because less water in your blood causes your kidneys to hold on to the urine.

Does dehydration cause cramping?

Loss of electrolytes, like sodium and potassium, can cause cramping. They’re expelled through perspiration (sweating). Drink water, but also a sports drink to replenish your electrolytes if your fluid losses are extensive from sweating, vomiting or diarrhea.

Can medications cause dehydration?

Diuretic medications, which are prescribed to treat heart failure and high blood pressure, can increase your risk of dehydration.

Can dehydration cause shortness of breath?

Shortness of breath is not a symptom of dehydration. However, it may go alongside dehydration. For example, you might be playing a sport outside in the hot sun and get dehydrated from lack of water and also feel short of breath from all the activity.

Care and Treatment

How is dehydration diagnosed?

Don’t forget that if you feel thirsty, you’re already dehydrated. That’s the easiest way to tell that you need more fluids.

Laboratory tests can also diagnose dehydration. Tests include:

• Low urine sodium concentration.
• Elevated plasma serum osmolality. This measures how concentrated some particles are in your blood plasma.
• Elevated creatinine. This tests kidney function.
• Elevated blood urea nitrogen. This also relates to kidney function.

What are the levels of dehydration?

Dehydration may be categorized 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 losses from vomiting and diarrhea. You should feel better after five or 10 minutes.
• Moderate. Moderate dehydration requires an IV (intravenous hydration). 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 or go to an emergency room.

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

How is dehydration treated?

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

How long does it take for the symptoms to stop after water is ingested?

You may see the symptoms of dehydration improve in as little as five to 10 minutes.

How do I prevent dehydration?

Exactly how much water do you need? That depends on your weight, age, level of activity, age, the climate of your environment and other factors. Those 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 (about 2.2 liters or 2.3 quarts per day for an adult female and about 3 liters or 3.2 quarts per day for an adult male), talk to your healthcare provider to confirm the right amount for you.

Keep 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 are properly hydrated is to check your urine. 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 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 are finished with the activity, you should drink more. How much more? To replace what you have lost: at least another 16 to 24 ounces.

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 the body can cause trouble. Muscle cramping may be due to a deficiency of electrolytes.

Beverages containing alcohol or caffeine aren't recommended for optimal hydration. These fluids tend to pull water from the body and promote dehydration. Fruit juice and fruit drinks may have too many carbohydrates, too little sodium and they may upset your stomach.

Adequate hydration will keep your summer activities safer and much more enjoyable. Keep an extra pitcher of water in the refrigerator and add fresh lemons, limes, cucumber or mint for a dash of flavor.

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, and more fun! 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.

When to Call the Doctor

When should I contact a healthcare provider about dehydration? At what point is dehydration dangerous?

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.

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

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 or go to the emergency room right away if you have symptoms of severe dehydration, or (see below) heatstroke:

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