12 Dehydration Symptoms Everyone Should Know, According to Experts

It doesn't take much to become dehydrated. Lose just 1.5% of the water in your body (the human body is usually about 60% H2O), and you've reached the tipping point of dehydration. Many things can cause dehydration—, and it can do much more to your body than just make you feel thirsty. Other symptoms include fatigue, smelly breath, and, you guessed it, dark-colored urine. But they don't stop there. Here, 12 dehydration symptoms everyone should know.

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Notice your breath smelling the opposite of minty fresh? It could be because you haven't drank enough water. Marshall Young, DDS, a dentist in Newport Beach, California, tells Health, "Saliva has important antibacterial properties. When dehydrated, the decreased saliva in the mouth allows bacteria to thrive, resulting in bad breath." Yikes. So drink up for your own sake...and for the people around you, too.

Dehydration can mask itself as hunger, or more specifically as sugar cravings. This may happen particularly if you've been exercising, Amy Goodson, RD, a sports dietitian who has worked with the Dallas Cowboys, tells Health. "When you exercise in a dehydrated state, you use glycogen, or stored carbohydrates, at a faster rate, thus diminishing your stores more quickly." So once you finish exercising, you will likely crave carbs (aka sugar) to help you replenish those glycogen levels. Pro tip: Before indulging your cravings, drink a tall glass of water and wait five minutes. You might not be as hungry as you think.

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Your skin will let you know if you haven't been drinking enough water, Anne Marie Tremaine, MD, a dermatologist at Skin Wellness Physicians in Naples and Marco Island, Florida, tells Health. Dehydrated skin will feel tight and appear dull when you look in the mirror. You may even notice more exaggerated wrinkles or darker under eye circles than usual. You can pinch your cheek as a test; if it wrinkles with gentle pressure instead of holding its shape, it's begging you for water. For smooth, moisture-rich skin, Dr. Tremaine also suggests keeping showers short (less than five minutes) and using only lukewarm water, as hot water can dry your skin out even more.

That mid-afternoon slump may have more to do with dehydration than you think. "When you're dehydrated, your blood pressure drops, heart rate increases, blood flow to the brain slows—all of which can make you tired," Luga Podesta, MD, a sports medicine specialist at Bluetail Medical Group in Naples, Florida, tells Health. Physical tasks may also feel more difficult and tiring because your muscles are lacking H2O.

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Cranky much? Drink a glass of water and your mood may change. "Neurological effects of dehydration can cause irritability," Dr. Podesta says. A small 2011 study published in the Journal of Nutrition tested mood and concentration in 25 young women who were either given enough fluids to remain properly hydrated, or who became mildly dehydrated by taking diuretics and exercising. The dehydrated women—who were at a hydration level that was just 1% lower than optimal—reported headaches, loss of focus, and irritability.

It may seem counterintuitive, but dehydration can bring on chills. "This occurs because your body starts to limit blood flow to the skin," Dr. Podesta says. In addition, water holds heat, so if you become hydrated it can be more difficult to regulate your body temperature, which can make you get chilly faster, even when you're not in a cold environment.

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When your body isn't getting enough water, it slows down blood circulation, which can make your muscles cramp up, Ray Casciari, MD, a longtime private practice pulmonologist, now with a medical technology company in Orange, California, tells Health. "The body will protect its vital organs, so it shifts fluid away from muscles and anything that's not vital," he says. Changes in sodium and potassium through sweat loss can also contribute to cramping. Cramps can be extremely painful and make muscles feel harder than normal to the touch.

Along with your muscles, your brain also gets less blood circulation when you're low on water, which can make you dizzy, Dr. Casciari says. Mild dehydration may also affect your ability to conquer mental tasks and cause you to feel foggy headed, according to a 2011 study from the British Journal of Nutrition.

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Dehydration can cause headaches in a couple of different ways. "Lack of water affects your body's serotonin levels, which can give you headaches," Dr. Casciari says. In addition, small blood vessels in the brain respond quickly to hydration levels (which is also the culprit behind those nasty hangover headaches), leading to dull aches and even full-blown migraines. Try downing a glass or two of water the next time you have a headache and you may find it disappears. You could also eat fruit, which contains a lot of water, Dr. Casciari suggests.

Your body needs water to keep things moving through your colon. When you're not getting enough H2O, your body compensates by withdrawing more fluid from stool, making it harder and more difficult to pass. That said, it's worth noting that drinking more water when you're already properly hydrated won't necessarily relieve constipation caused by other factors, like the medications you're taking, medical conditions, or a lack of fiber in your diet.

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One telltale sign of dehydration is dark yellow urine, Peter Shearer, MD, an emergency physician and chief medical officer at Mount Sinai Brooklyn, tells Health. When you're dehydrated, your kidneys, which filter waste, tell your body to retain water. That means you'll have less water in your urine, causing it to become more concentrated with waste products and therefore darker. If you notice your urine is darker than usual, reach for your water bottle.

It might seem obvious, but being thirsty is your body's number one cue to drink more water, Dr. Shearer says. When you get dehydrated, you'll naturally be thirsty, he explains, so listen to your body's signals and rehydrate until you've quenched your thirst.

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