According to MedlinePlus, dehydration doesn’t just mean your body is losing water — it also means you're losing electrolytes, such as sodium, magnesium, and potassium, all of which you need to breathe, move, talk, and generally stay up and running.

As MedlinePlus points out, certain health conditions, including diabetes, can put you at an increased risk of dehydration. If you’ve been sweating too much because of the heat or overexertion, urinating frequently, or throwing up or having diarrhea because of the flu or another acute illness, it’s especially important to pay attention to replenishing your water reserves.

People who are especially vulnerable to dehydration include those who are unable to quench their thirst because of disability or disease, athletes, and those who are simply too young or too old to replace lost fluids on their own, according to NHS Inform. Men who are middle-aged or elderly may be at particular risk of complications from dehydration, according to a small study published in the Journal of Physiology in November 2020. (The study did not involve women.) The researchers found that over time, the body becomes worse at detecting markers of dehydration (such as high levels of salt in the blood), and without these signals, older adults may not realize they are dehydrated or drink fluids to rehydrate. Untreated dehydration can cause the heart rate to increase, straining your ticker.
Extreme dehydration — defined by the World Health Organization as a loss of more than 10 percent of your body weight in fluid — can lead to injury or fatal complications, and it requires an ER visit. Seizures, cardiac arrhythmia, or hypovolemic shock can occur because your blood volume is too low.

Yet it rarely comes to that. Most of the time, you can easily replenish your fluid stores and fend off dehydration when you drink water throughout the day. Thirst, headache, and dry mouth are all signs it’s time to reach for water or a sports drink that’s low in sugar and high in electrolytes, says MedlinePlus. 

But the signs of dehydration aren’t always so obvious. Here are six surprising signs and symptoms of dehydration.

1. Bad Breath Is a Possible Warning Sign of Dehydration
Saliva has antibacterial properties, but dehydration can prevent your body from making enough saliva, per the Better Health Channel.

“If you’re not producing enough saliva, you can get bacterial overgrowth in the mouth, and one of the side effects of that is bad breath,” says John Higgins, MD, a professor of at the University of Texas in Houston and the chief of cardiology at Lyndon B. Johnson General Hospital.

It’s the same reason you may wake up with “morning breath”: Saliva production slows down during sleep, notes the Mayo Clinic, leading to an unpleasant taste in the mouth as bacteria grow. So the next time you experience dry mouth and your breath smells less than fresh, it may be time to rehydrate.

2. Dry or Flushed Skin Could Be a Symptom of Dehydration
“A lot of people think that people who get dehydrated are really sweaty, but in fact, as you go through various stages of dehydration, you get very dry skin,” Dr. Higgins says, adding that skin may appear flushed as well.

Another key skin-related symptom of dehydration is a loss of skin elasticity, according to MedlinePlus. This can cause skin to remain “tented” after being pinched, taking some time to return to its normal appearance (more on that below).

3. Muscle Cramps Are a Dehydration Symptom, Likely From Heat Illness
When your body loses enough fluid, it’s unable to cool off adequately, leading to heat illness, notes OrthoInfo. One symptom to watch for is muscle cramps, which can happen during exercise, particularly in hot weather.

“The hotter you get, the more likely you are to get muscle cramps, and that’s from a pure heat effect on the muscles. As the muscles work harder and harder, they can seize up from the heat itself. Changes in the electrolytes, such as sodium and potassium, can lead to muscle cramping as well,” says Higgins.

Bear in mind that when it comes to rehydration after exercise, all drinks may not be created equal. A study published in March 2019 in BMJ Open Sport and Exercise found that when participants rehydrated with a drink containing electrolytes after exercise, they were less likely to develop muscle cramps. Participants who drank plain water, on the other hand, were more likely to have cramps. The study was small, so its findings may not apply to you, but the next time you feel a muscle cramp coming on after exercise, opt for an electrolyte-filled sports drink.

Even in cooler weather, dehydration is possible if you don’t replace lost fluids by drinking small amounts of water while working out. Higgins says symptoms may be milder or come on slower, but dehydration carries the same risks, regardless of the temperature outside.

4. Fever and Chills Are Symptoms of Heat Illness, Which Causes Dehydration
Other symptoms of heat illness include fever and chills. Excessive sweating combined with your skin feeling cool to the touch may be signs of heat exhaustion, according to the Centers for Disease Control and Prevention (CDC).

Fever can worsen dehydration. The higher the fever, the more severely dehydrated you may become. Unless your body temperature decreases, your skin will lose its cool clamminess and then become hot, flushed, and dry to the touch. At this point, it’s important that you cool yourself down immediately and see a medical professional, the CDC advises. Applying ice and cool, wet cloths, and moving to a cool area are short-term strategies until you can get medical attention.

According to the Mayo Clinic, children and infants lose more of their body fluid to fever, and they are more likely to experience severe diarrhea and vomiting from illness. An infant or young child may also have other dehydration-related symptoms, such as a soft spot on their head, no tears when they cry, or fewer wet diapers than normal. Any fever in an infant or toddler is cause for concern. Ask your pediatrician for advice on when to call the doctor in these circumstances. 

The CDC urges adults with fever to seek help if their temperature reaches 103 degrees F. This could be a medical emergency. 

5. Food Cravings, Especially for Sweets, May Just Mean You’re Thirsty
“When you’re dehydrated, it can be difficult for organs such as the liver, which uses water, to release glycogen [stored glucose] and other components of your energy stores, so you can actually get cravings for food,” Higgins says.

While you can crave anything from chocolate to a salty snack, cravings for sweets are more common because your body may be experiencing difficulty breaking down glycogen to release glucose into the bloodstream to use as fuel, he says.

6. Headaches Could Be a Sign You Need to Drink More Water
As MedlinePlus points out, even mild dehydration can cause a headache. Although various factors besides dehydration can cause headaches, drinking a full glass of water and continuing to sip more fluids during the day is an easy way to ease your pain if, in fact, dehydration is the culprit.

Are You Dehydrated, or Is It Something Else?
If you’re thirsty, you’re already dehydrated. But lack of thirst doesn’t necessarily mean you’re well hydrated. Here are two other ways to check your hydration.

Try this skin test. Use two fingers to pinch up some skin on the back of your hand, and then let go. The skin should spring back to its normal position in less than a couple of seconds. Higgins says that if the skin returns to normal more slowly, you might be dehydrated, per MedlinePlus.

Check your urine. If you’re well hydrated, your urine will be mostly clear with a tinge of yellow (the color of light lemonade before it hits the bowl). Darker yellow or orange are the “warning” colors to watch for, per  UC San Diego Health. If your pee is dark, start drinking fluids. (On the flip side, clear or transparent urine could mean you’re getting too much water.)

Tips for Staying Hydrated
When it comes to daily water intake, hard-and-fast rules are difficult to apply because the amount of fluid you need depends on so many factors, including your age, gender, whether you’re pregnant or breastfeeding, and whether you have any underlying medical conditions or chronic illnesses.

The 2004 guidelines from the National Academies of Sciences, Engineering, and — the most recent available — advise 2.7 liters of water per day for women and 3.7 liters per day for men. You can reach this amount by consuming certain foods, water, and other fluids.

Here are some tips for getting all the liquid you need and prevent dehydration.

Keep Your Water Bottle Handy at All Times
Accessibility can make a difference. This can be as simple as carrying a water bottle with you. “If it's right next to you, you'll likely get into the habit of sipping it without even realizing it,” says Johannah Sakimura, RD, an outpatient oncology dietitian at Overlook Medical Center in Summit, New Jersey.

Try Spicing Up Plain Water
While it’s important to drink plenty of water, not everyone enjoys it straight. “If you don't love plain water, jazz it up by adding a splash of fruit juice or chunks of fresh or frozen fruit,” says Sakimura. “Or try naturally flavored calorie-free seltzers — their fizz and fruit flavor make them more appealing than plain flat water.”

Turn to Sugar-Free Herbal Tea or Coffee
Sakimura recommends unsweetened teas, which are available in lots of different flavors. “Sip fruity iced teas during the day (with lots of ice if it's hot out), or cozy up with a mug of hot peppermint or chamomile tea at night — they all count toward your daily fluid goal.”

And if your beverage of choice is coffee rather than tea, that works, too: While caffeine may have a diuretic affect, increasing your need to urinate, one crossover study of 50 men found that there were no significant differences in total hydration when the men drank four cups of coffee daily compared with four cups of water. The results of the study, which were published in the journal PLoS One, suggest that coffee hydrates similarly to water when consumed in moderation by regular coffee drinkers. 

While this particular study exclusively focused on men who drank coffee, the Mayo Clinic notes that caffeinated beverages can still help all adults achieve their daily hydration goals — just be sure to consume no more than 400 milligrams (mg) per day. Symptoms such as upset stomach, frequent urination, and insomnia could mean you’re drinking too much coffee. 

Swap Your Packaged Snacks for Fresh Options 
“Swap dry snacks, like chips, pretzels, and crackers — which have a very low water content — with refreshing munchies, like fresh or frozen fruit, yogurt, healthy smoothies, celery with peanut butter, and cut veggies with hummus,” recommends Sakimura.

Pile on the Produce 
In the same vein, know that those veggies and fruits are hydrating, just like liquids. “Aim to make half your plate produce at meals. All those vegetable and fruit servings will supply water as well as a hearty dose of vitamins, minerals, and fiber,” says Sakimura. “In fact, some fruits and vegetables are more than 90 percent water — including cantaloupe, strawberries, watermelon (of course), cucumber, celery, lettuce and leafy greens, zucchini, tomatoes, and bell peppers.”

Sip More Fluid During Meals
“Sipping water with meals will help you eat more slowly, pace your eating, and, of course, stay hydrated,” Sakimura says. Drinking water before eating may furthermore help with weight loss, as it did for participants of a study published in the journal Obesity. During a small randomized controlled trial involving 84 subjects, participants who drank 500 milliliters (ml) of water 30 minutes before eating lost an average of 1.3 kilograms (kg) at the 12-week follow-up.

A Final Note on the Importance of Preventing Dehydration for Older Adults
Older adults may be at a greater risk of dehydration for a number of reasons, per the National Council on Aging (NCOA). For one, you may experience a decreased sense of thirst as you age, which can in turn diminish your daily water intake. Some older adults become chronically dehydrated if they take certain , such as diuretics, are not able to get themselves a glass of water easily, or forget to drink because of a health issue such as dementia. Chronic dehydration in an older adult may lead to confusion, low blood pressure, dizziness, and constipation.

If you have an elderly relative with mobility limitations or cognitive problems, be sure to watch them for signs of dehydration, or ask their caregivers to do so too, and make sure that they drink enough water. As for your own well-being, remember that the human body is composed of at least 60 percent water, notes the U.S. Geological Society. Keep that healthy balance, and drink up!