6 Surprising Signs You Need to Drink More Water

Bottoms up! Staying properly hydrated offers radiant skin, fresh breath, mental clarity and more.

Medically reviewed in November 2022

Updated on November 18, 2022

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You may think that your body will always let you know the optimal time to replenish your fluids. But the fact is, thirst isn’t a foolproof sign of dehydration. Among other factors, your age, the weather, and your activities can all interfere with your thirst response. 

This is important to recognize because losing just 1.5 percent of your total water weight is considered “mild dehydration.” Dehydration can lead to fainting, accidents, injuries, and more. So, aside from feeling thirsty, how else can you tell when it’s time to drink up? 

Here are helpful tips about dehydration and some red flags to look out for. Grab a cool glass of H2O if you experience any of these surprising signs.

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Brain fog and exhaustion

Not on your A-game today? Even slight dehydration could be to blame. A 2018 analysis published in Medicine & Science in Sports & Exercise found that mild dehydration was linked to impaired cognitive performance, coordination, and executive function, or our ability to focus, remember things, and multi-task.

It can also cause fatigue, worsen mood, and lead to headaches, according to a 2012 study published in The Journal of Nutrition. The risks of severe fluid loss are well known, but for this study, researchers were curious about the mild dehydration you might experience in daily life. How risky is it really if you skip a few glasses of water? Researchers controlled hydration levels in 25 young women at rest and during exercise. The women who were less hydrated scored lower on mood and reasoning tests. They also reported difficulties concentrating and completing their work on those days.

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Hunger you just can’t satisfy

Mild dehydration can mask itself as hunger and might make you more prone to sugar cravings. The reason why is up in the air—researchers need to learn more about how hunger and thirst sometimes get confused.

On the other hand, staying well hydrated can trick you into feeling full, says Samuel Nickles, MD, a surgeon at Palmetto Adult and Children’s Urology in North Charleston, South Carolina. Your satiety level, or feeling of fullness, is influenced by your stomach contents—regardless of whether you consume solids or liquids. That means drinking water could curb your appetite, he explains.

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Bad breath

Saliva keeps your mouth naturally fresh by rinsing away odor-causing bacteria and food particles. Dehydration can allow germs and debris to build up on mouth surfaces and contributes to foul-smelling vapors. 

Prevent bad breath by:

  • Sipping from a personal water bottle throughout the day
  • Munching on high-fiber, high-water-content fruits and vegetables like apples, pears, and carrots
  • Chewing sugar-free gum between meals to stimulate saliva production
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Dry, flaky skin

Dehydration can prevent a layer of your skin called the stratum corneum from receiving the moisture it needs. That can lead to skin having a dull appearance, along with stretched pores, fine lines, and flakiness.

Even if your skin is oily, it’s still possible to be dehydrated. In fact, dehydrated skin is prone to excess oil and breakouts, as oil glands try to make up for the lack of moisture.

Keep your skin glowing by:

  • Drinking a large glass of water instead of, or before, your morning coffee
  • Skipping nicotine, alcohol, and excess caffeine
  • Avoiding long, hot showers and baths, which can wash away your natural oils and dry your skin out even further
  • Applying moisturizer as soon as you get out of the bath
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“Dehydration may cause your blood pressure to drop, which can reduce vascular tone in your brain and may lead to headaches,” says Nickles. 

Vascular tone refers to how tight your blood vessels are. Low blood pressure means less blood and less oxygen being carried to brain cells; the vessels in your brain widen to try to increase the flow. These changes can trigger migraine headaches.

You may also experience what’s known as a dehydration headache if you’re not getting enough fluids. In addition to symptoms of dehydration like thirst and dark-colored urine, you may have a dull headache with pain that increases when you move your head. You may feel pain anywhere around the head, but not likely in the face, sinuses, or back of the neck.

Remedies include avoiding alcohol and caffeine, reducing physical activity to cut down on sweating—and, not surprisingly, boosting your fluid intake.

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Urine color

“Urine color is influenced by several factors, including hydration,” says Nickles. “Typically if your urine is a pale straw-yellow, it means you’re well hydrated. If it becomes a little too yellow, it means you should drink some water.”

Here’s what your pee color could indicate:

  • Clear or pale straw-yellow: You’re a hydration all-star. Keep up the good work. 
  • Honey or yellow: You may be mildly dehydrated. Take some sips.
  • Dark yellow, amber, or orange (along with less frequent urination): You’re more severely dehydrated, or you could have a condition that requires medical attention. Drink plenty of water and call your healthcare provider (HCP) if the dark color persists. 
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How much water do you need in a day?

The common advice to aim for eight glasses a day isn’t actually based on hard science. The truth is, the amount of water you need varies depending on your age, health, activity level, sex, and other factors, including whether you are pregnant or breastfeeding. 

Roughly speaking, however, if you’re a healthy adult male living in a temperate climate, 3 liters (13 cups) of water a day should keep you hydrated, according to the Institute of Medicine. For healthy adult women, 2.2 liters (9 cups) should do the trick. 

The recommended intake for all fluids—including those found in food—is 3.7 liters per day for men, and 2.7 for women. Remember that all fluid you consume counts toward this daily total, whether that comes from water, sports drinks, or tea. Food provides about 20 percent of your total water requirement.

And it is possible to have too much of a good thing, even when it comes to hydration. If you have certain health conditions—such as heart disease or thyroid, adrenal, kidney, or liver disease—ask your HCP about the right amount of water for you.

Slideshow sources open slideshow sources

Riebl SK, Davy BM. The Hydration Equation: Update on Water Balance and Cognitive Performance. ACSMs Health Fit J. 2013 Nov;17(6):21-28.
Cleveland Clinic. Dehydration. Reviewed February 16, 2021.
Wittbrodt MT, Millard-Stafford M. Dehydration Impairs Cognitive Performance: A Meta-analysis. Medicine & Science in Sports & Exercise. November 2018. 50(11): p2360-2368.
Armstrong LE, Ganio MS, et al. Mild Dehydration Affects Mood in Healthy Young Women, The Journal of Nutrition. February 2012. Volume 142, Issue 2, Pages 382–388.
Kaiser Permanente. 10 warning signs of dehydration. May 13, 2022.
PKD Foundation. Hunger vs. thirst: tips to tell the difference. Accessed November 17, 2022.
Corney RA, Sunderland C, James LJ. Immediate pre-meal water ingestion decreases voluntary food intake in lean young males. Eur J Nutr. 2016 Mar;55(2):815-819.
Rutgers New Jersey Agricultural Experiment Station. Signs You are not Drinking Sufficient Water. March 2019.
Better Health Channel (AUS). Halitosis or bad breath. Reviewed August 31, 2022.
Van der Sluijs E, Slot DE, et al. The effect of water on morning bad breath: a randomized clinical trial. Int J Dent Hyg. 2016 May;14(2):124-34. 
Mayo Clinic. Does drinking water cause hydrated skin? November 21, 2020.
American Skin Association. Dry Skin. Accessed November 17, 2022.
Cleveland Clinic. Dehydration Headache. Reviewed December 3, 2021.
Cleveland Clinic. What The Color of Your Pee Says About You. November 8, 2021.
NSW Health. Urine Color Chart. April 7, 2022.
Mayo Clinic. Water: How much should you drink every day? October 12, 2022.
Academy of Nutrition and Dietetics. How Much Water Do You Need. Reviewed June 2022.

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