Here’s How to Tell If You Are Dehydrated

It’s been drilled into you since you were a kid: You need to drink enough water. Something that’s often not included in that life lesson? How to tell if you are dehydrated.

While you probably do your best to keep the liquids coming, the signs of dehydration can easily sneak up on you, especially if you forget to load up on water after a really sweaty workout or when it’s especially hot or humid outside, according to the Mayo Clinic.

“Our bodies need water and other fluids to function properly, and if you become dehydrated, some of these processes may not function normally,” women’s health expert Jennifer Wider, M.D., tells SELF. “Severe dehydration can have dire consequences.” After all, water typically makes up two-thirds of your bodyweight, per the U.S. National Library of Medicine.

Ahead, SELF asked experts to break down the difference between everyday thirst and true dehydration—plus the dehydration symptoms to keep on your radar, because they’re not always super obvious.

Your body does a pretty good job of maintaining its fluid balance under normal circumstances. You pee when you have too much water, and get thirsty when you need more, Kelly Pritchett, Ph.D., RDN, CSSD, exercise physiologist and assistant professor in nutrition and exercise science at Central Washington University in Ellensburg, tells SELF.

“Everyone experiences thirst. It’s your body telling you that you need more fluids,” Cedric Dark, M.D., assistant professor of emergency medicine at Baylor College of Medicine, tells SELF. “However, dehydration is a pathological process when your body has lost too much fluid, either through sweating or in the urine—due to drugs like caffeine and alcohol, which function as diuretics—or hasn’t taken in enough fluids.”

Put more simply, dehydration means there isn’t enough water in your body to efficiently carry on vital processes such as delivering oxygen, regulating your body temperature, and digesting food, according to the Cleveland Clinic.

Thirst, as you’ve likely experienced, is a common symptom of dehydration, Nadia Khan, M.D., an internal medicine physician at Northwestern Medicine Central DuPage Hospital in Winfield, Illinois, tells SELF. “By the time you feel thirsty, you may already be moderately dehydrated,” she says.

“It’s challenging to stay hydrated, even when you’re healthy,” Sanford Vieder, D.O., medical director of Lakes Urgent Care in West Bloomfield and Livonia, Michigan, tells SELF. “The vast majority of us don’t drink as much water as we should.”

It’s easy to associate dehydration with being overheated as well, but that’s not always the case. The following factors can also cause dehydration, per the Mayo Clinic:

• Diarrhea and vomiting: Severe diarrhea can cause you to lose a lot of fluids and electrolytes (essential minerals in your body) quickly. If you’re vomiting at the same time—say, due to a case of food poisoning or a stomach virus—you’ll lose even more fluids.
• Fever: Your risk of dehydration rises as your temperature does since your body is rapidly trying to cool itself down.
• Excessive sweating: Sweat is fluid making its way out of your body. If you’re working out hard, especially in hot, humid weather, and you don’t replace those fluids you’re losing, you can become dehydrated.
• Frequent urination: Needing to pee all the time can be the result of numerous underlying health conditions, like undiagnosed or uncontrolled diabetes, or if you’re taking certain medications like diuretics or certain blood pressure drugs. Of course, as you pee throughout the day, fluids leave your body and increase your risk of dehydration.

Older adults (who are less likely to drink enough fluids) and young children (who have higher energy needs and are more likely to deal with diarrhea and vomiting) also have a higher risk of becoming dehydrated, per the U.S. National Library of Medicine.

The signs and symptoms of dehydration can be pretty obvious or seemingly random. Here’s what you might experience when your body needs more fluids:

Your body likes to maintain an optimal balance of fluids to ensure different parts, from your joints to your intestines, function properly, Mark Conroy, M.D., an emergency medicine physician at The Ohio State University Wexner Medical Center, tells SELF.

“Your muscles also require a certain amount of water to function well,” Dr. Conroy explains. When you’re dehydrated, your body will “pull water out of that muscle tissue, along with electrolytes,” he says, which can lead to painful muscle cramps.

This is often due to a ​​sodium deficit in the body. “Exertional heat cramping, or full-body cramping, may be related to sodium depletion and fluid loss especially in individuals who are ‘salty sweaters,’” Pritchett says. In this case, particularly for endurance exercise like long-distance running, sipping on an electrolyte sports drink (or even just having a salty snack with water) can be helpful to restore the natural mineral balance in the body.

The exact reason why dehydration sometimes causes a headache isn’t known. One theory is that dehydration alone doesn’t directly lead to headaches but may exacerbate underlying conditions like migraine.¹ There’s also “potentially a slight, temporary contraction of the brain due to low hydration levels,” which doesn’t necessarily feel great, Dr. Khan says.

When you’re dehydrated, your blood vessels contract and your body tries to pull fluid to more centrally located organs, like your heart and brain, to keep them running properly, Dr. Conroy explains. This means the rest of your body may start to operate at a slower pace, making you feel sluggish and tired. “Fatigue is your body noticing it doesn’t have an optimal state,” Dr. Conroy says.

The low blood pressure that comes with dehydration can also make you feel woozy, Dr. Khan says. A lower level of electrolytes can also cause dizziness or a lightheaded feeling.

Under normal, well-hydrated circumstances, your urine should be a pale yellow with little-to-no odor.² When you’re dehydrated, though, you’ll be able to tell (or shall we say smell) when you do go, as you’ll likely be peeing less than you normally would. “As you become dehydrated your body seeks to conserve fluids by reducing urine output and concentrating the urine,” Dr. Dark says. “Thus, it appears darker and in lower volume.”

Remember, dehydration shifts your body into survival mode, so it tries to shuttle water to the areas where it’s most needed, Dr. Khan says. “Water is diverted from nonvital organs such as the skin to more vital ones like the heart, brain, and kidneys,” she explains. As a result, places like your mouth and lips might start to feel really dry.

Saliva has bacteria-fighting properties, Dr. Wider explains. When you’re dehydrated, your saliva levels go down because your body is using fluids where it needs it the most, meaning your mouth’s ability to fight odor-causing germs may not be as efficient. If you notice that you suddenly have bad breath for no reason, try drinking more water regularly. Fixing the dry mouth alone may freshen things up.

Along those lines, a white tongue can also be a sign of dehydration. But it can also be a symptom of many other things—from poor oral hygiene or mouth breathing to conditions like oral thrush—so it’s best to see your doc to make sure it’s nothing to worry about, according to the Mayo Clinic.

Feeling briefly confused or out of it can simply mean you need a bit more sleep. But if you haven’t had enough water, it can also be a tip-off that you’re dehydrated, Dr. Vieder says. Confusion is usually not something that comes on suddenly unless you’re working up a sweat on a hot day, Dr. Vieder adds, so if it happens rapidly and is paired with other concerning symptoms like a fast pulse, fever, slow or rapid breathing, or uncontrolled shivering, it’s best to seek immediate medical attention, according to the U.S. National Library of Medicine.

Your liver needs water to function properly. When it doesn’t get it, it signals to your brain that you need fuel, Dr. Wider says. Instead of craving water, though, it tends to make you think you’re hungry, even if you’ve had plenty of food to eat.

If you grab the skin on the back of your hand, pull it up, and let it go, it should quickly snap back into place. But this doesn’t usually happen with people who are dehydrated. “If it stays tented or resumes its shape more slowly than usual, that’s a really good sign of being dehydrated,” Dr. Vieder says. Without enough moisture, your skin loses some of the elasticity it needs to snap back.

It seems that this would be a sign that you’re not dehydrated, but Anthony J. Brutico, D.O., medical director of the Emergency Department at New Jersey’s Newton Medical Center, tells SELF it can be a marker of heat exhaustion or heat stroke. This typically happens because your “volumes of fluid are so low that the body is trying to hold on to what you have,” he explains. If this happens to you, seek medical attention immediately, as heat-related illness can cause permanent disability or even death in severe circumstances, according to the Centers for Disease Control and Prevention.

It’s worth saying again: If you’ve stopped sweating and you’re in hot conditions, you want to seek help immediately, Dr. Brutico says. You should also get to a doctor if you’re not acting like yourself, you feel like you’re going to faint, or you actually have fainted. In those cases, Dr. Brutico recommends drinking liquid and heading to the ER to get evaluated (just be sure to avoid driving yourself at this point). You may need IV fluids to get rehydrated.

If you or someone you’re close to can’t get to the ER and needs to wait for help due to heat-related symptoms, the CDC recommends the following steps after calling 911:

• Move the affected person to a shaded, cool area and remove outer clothing.
• Rapidly cool the body with cold water or an ice bath if possible. You can also wet the skin, place cold, wet cloths on the skin, or soak clothing with cool water.
• Circulate the air around the affected person to speed cooling.
• Place cold, wet cloths or ice on the head, neck, armpits, and groin; or soak the clothing with cool water.

It’s important to remember that you can also become dehydrated outside of hot conditions, such as when you have diarrhea or a stomach bug. In those cases, dehydration may not be a sudden thing, but slightly more gradual. A few other signs it’s time to seek medical attention, per the Mayo Clinic:

• You’ve had diarrhea for 24 hours or more.
• You’re irritable or disoriented.
• You feel lightheaded or faint.
• You’re much sleepier or less active than usual.
• You can’t keep down fluids.

Even if you’re only experiencing the less severe symptoms of dehydration, it’s time to get some water or an electrolyte drink in you ASAP. Take a pass on soda and other heavily sweetened drinks, as these can potentially dehydrate you even more, Dr. Vieder says.

The Institute of Medicine of the National Academies of Sciences³ suggests that adequate water intake includes 2.7 liters (11 cups) to 3.7 liters (almost 16 cups) per day—and yes, all fluids count toward that number, including from the food you eat. Keep in mind that the amount of water you need in a day is unique to you based on factors like exercise, whether or not you work in hot conditions, and even your diet, as certain beverages like coffee cause you to pee more than usual.

To stay hydrated, Dr. Conroy recommends keeping a water bottle with you when you’re on the go. If you’re not sure that you’ll do a good enough job of hitting your daily hydration goal, pick up a water bottle that has notches to measure how much you’ve actually had.

If you’re really committed, you can even set reminders on your phone or desktop calendar to drink water throughout the day. “Make sure to drink more if exercising or sweating, and try to drink a glass of water with each meal,” Dr. Khan says. Keep tabs on your pee, as well. If it’s deeply yellow or oddly pungent, that’s probably a sign you need to load up on more liquids.

Still need some motivation? Try these expert-approved tricks to drink more water every day.

Sources:

1. Nature Public Health Emergency Collection, Dehydration and Headache
2. U.S. Army Public Health Command, Are You Hydrated? Take the Urine Color Test
3. Institute of Medicine of the National Academies of Sciences, Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate

Related:

• 13 Infused Water Recipes That Will Help You Drink Way More Water
• Here’s When to See a Doctor About Diarrhea and When to Wait for It to Pass
• Can Severe Dehydration Really Make You Pass Out?