Why Are You Dehydrated? 8 Common Reasons

You may need more water than you might think
dehydrated woman drinking water

We all need to drink water — typically more than we realize. So, what if you drink loads of water each day but are still feeling thirsty and dehydrated?

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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.

Emergency medicine physician Baruch Fertel, MD, explains dehydration and what can cause it. 

What is dehydration?

Between 55% to 78% of your body is made of water. When you’re dehydrated, you have a lack of water in your body and your body doesn’t have enough water to perform its necessary functions.

This can be from not drinking enough water or when you lose water quickly from sweating, vomiting or diarrhea and don’t match the losses.

Water helps aid in digestion, lubricates your joints, makes saliva, delivers oxygen throughout your body, regulates your body temperature and balances your body’s elements.

So, it’s important to watch out for signs that you’re not drinking enough water.

“If you notice that you haven’t urinated for a few hours or if your urine, when you do urinate, is very dark, very concentrated, that may be a sign that you’re not drinking enough,” says Dr. Fertel.

Signs you might be dehydrated:

  • Decreased urine output.
  • Concentrated urine that’s dark-colored.
  • Headache.
  • Nausea.
  • Muscle cramps.
  • Fatigue.
  • Dizziness, light-headedness.
  • Dry mouth.
  • Constipation.

Dehydration can lead to heat exhaustion, in which your body temperature begins to rise.

“It can cause a slowdown in some of the body’s metabolic processes,” says Dr. Fertel. “You need to get out of the warm weather and take in more fluid to prevent a progression to a more serious state, which is heatstroke. Heatstroke can be life-threatening.”

Reasons you’re dehydrated

So, you’ve been trying to drink more water, but you’re still feeling dehydrated. Here are a few reasons why.

You’re not drinking enough water

Seems obvious, right? But a lot of times, you may think you’re getting enough water each day. But in reality, you’re coming up short.

How much water do you need to drink each day?

The National Academies of Science, Engineering and Medicine recommends the following for daily fluid intake:

  • 125 ounces (3.7 liters) for men.
  • 91 ounces (2.7 liters) for women.

But Dr. Fertel warns that it’s not that cut and dry. “I don’t think those guidelines are that helpful because that’s for a normal person with average weight in a normal situation,” says Dr. Fertel.

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How much water you need to drink is unique to your situation, depending on the amount of energy you use. Factors can include how much you exercise, how much you sweat and how much fruit and vegetables you eat.

“A general rule of thumb is drink when you’re thirsty,” says Dr. Fertel. “If you’re thirsty, drink.”

People who are older, young children or those who may have a decreased thirst mechanism should be encouraged to drink liquids.

You have an electrolyte imbalance

While water is important, you also need to get electrolytes — think sodium, potassium, calcium and magnesium chloride — from fruits and vegetables.

“Water has hydrogen and oxygen, but it doesn’t have the electrolytes we need for the body,” explains Dr. Fertel.

Eating foods like bananas and apples not only helps hydrate your body, but also provides those essential electrolytes that help regulate nerve and muscle function, blood flow and brain function. Electrolytes also help regulate how much water stays in the cells of your body.

Sports drinks or other rehydration solutions can help restore electrolyte losses from sweating.

You’re drinking water all at once

If you wake up and chug a gallon of water each morning, you may be doing more harm than good.

Overloading your system with water will only cause your body to eliminate any excess through your urine — taking vital electrolytes with it.

Instead, aim to stay hydrated throughout the day.

You’re sweating too much

Whether you’re exercising or just out in the heat, sweating causes a loss of fluids and electrolytes. Unless you drink more water to replenish what you’ve lost, it can lead to dehydration.

“Remember, we can lose fluid by sweating and by breathing,” notes Dr. Fertel. “So, it’s important to stay hydrated.”

You’re drinking coffee or soda

While it’s tempting to slurp down that iced mocha and think you’re properly hydrated, it’s not that easy.

Drinks like coffee, sodas with caffeine — and even alcohol — can have a diuretic effect, meaning they can cause you to urinate or pee more, which can then further dehydrate you.

That’s not to say you can’t have a morning cup of joe, but there’s no substitute for plain old aqua.

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You’re sick

Battling a bug? Dealing with a virus can also cause you to feel dehydrated. Vomiting, sweating and having diarrhea can each cause a loss of fluids.

Instead of drinking large quantities of water all at once, you may want to sip on fluids throughout the day as it may be easier for your body to handle. Think sports drinks, tea or chicken broth.

“The beauty of chicken soup is that it has salt, which helps keep the water in the body,” says Dr. Fertel.

Your medication

Certain medications may make it easier for you to become dehydrated.

If you take diuretics, antacids, laxatives and blood pressure medication, they may be designed to flush water and electrolytes out of your body.

It’s important to talk to your doctor if dehydration is listed as a side effect.

“If you have heart failure or issues with fluid retention, talk to your doctor about optimal fluid regimens to remain hydrated in hot or warm weather,” advises Dr. Fertel.

You have diabetes

If you’re urinating frequently and always seem thirsty, it could be an early sign of diabetes.

Your body is attempting to get rid of sugar; hence, the frequent urination. And it can lead to dehydration. Your urine may be sweet smelling and it may be accompanied by weight loss.

“You may also have a metallic taste in your mouth and a smell that’s sweet, fruity or similar to nail polish remover,” explains Dr. Fertel.

What to do about it

You can avoid dehydration by staying hydrated throughout the day. Easier said than done, maybe. But here are a few tips to help keep your fluid intake up.

  • Track your fluid consumption. Whether you use a water-tracking app or a water bottle that marks the ounces consumed, it’s a good idea to get a baseline of how much water you drink and then aim to increase from there.
  • Set reminders. A water-tracking app should also have a reminder function and either send a notification to your phone or smartwatch. You can also use your alarm on your phone to set up reminders.
  • Drink a glass of water before meals. By doing so, you’ll increase the amount of water you drink each day by three glasses. A bonus? Sometimes, your body can confuse thirst for hunger. Having a glass of water before each meal can help you figure out how hungry you actually are.
  • Add flavor. If you don’t like the taste of water, consider adding fresh fruit, drinking carbonated flavored water or using powder or liquid water enhancers. Just watch out for added sugar and artificial sweeteners.
  • Eat foods high in water. Fill your diet with fruits and vegetables that are known to have high water content. Options include lettuce, watermelon, celery and cantaloupe.
  • Don’t forget about electrolytes. If you’re working out in the heat or sweating a lot, consider drinking fluids with electrolytes like pickle juice, sports drinks or chicken soup.

The levels of dehydration can be mild to severe. If you’re thirsty, drink water. You may start to see symptoms of dehydration improve in five to 10 minutes.

But if you’re experiencing signs of moderate or severe dehydration, it’s important that you seek medical treatment immediately. An intravenous hydration (IV) can help replenish fluids and your doctor can run tests. 

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