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15 Ways to Tell If You're Dehydrated

During these summer months, COVID-19 isn’t the only thing to be concerned about.

Dehydration—when the level of water in the body drops below what is necessary to function properly—isn't just a case of dry mouth or feeling a little parched. In hot weather, it can quickly become a serious medical condition that affects vital body systems like the brain and heart. Chronic dehydration can cause symptoms that seriously affect your quality of life. The first step in preventing it is to recognize it: These are 15 of the things that dehydration does to your body.


Your Skin Flushes

Face of a beautiful adult sad woman with long dark hair holding her hand near her neck.

An early sign of dehydration can be flushed skin, a signal that the body needs more water to quell inflammation. 


Your Body Temperature Rises


Without enough of the body's natural coolant—water—dehydration may cause you to develop a fever. If this is the case, hydrate and move to a cool environment immediately. A cool shower, bath or cool, wet compresses can help bring an elevated temperature down. If you or someone you're with has a fever over 102F, seek medical help right away. 


Your Muscles Cramp

muscle cramp

"Heat cramps" are caused by exertion in very hot environments. Excessive sweating can deplete your electrolytes, which can cause muscles to seize up. These cramps are most commonly felt in your arms, legs, abdomen or back.


You May Get Thirsty

Close-up of pretty young woman drinking water from glass

As you become depleted of fluids, your body may send a "check engine" signal in the form of thirst, nudging you to drink some water. But that's not always the case; dehydration can sneak up on you, and your first sign can be one of these other symptoms.

A good rule of thumb, especially during hot weather: Don't wait until you're thirsty to drink water.


Your Urine Darkens

hand of a woman closing the lid of a toilet

Urine should be clear or very light yellow; that's a sign that your kidneys are getting enough fluid to do their job. If your urine is a darker yellow, it can indicate that you're dehydrated.

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You Feel Dizzy or Weak

man massaging nose bridge, taking glasses off, having blurry vision or dizziness

Dehydration can cause your blood pressure to drop and less blood and oxygen to reach the brain. That can leave you with feelings of dizziness or weakness. If you or someone you're with faints or loses consciousness, seek medical attention ASAP.


You Feel Nauseous

Young vomiting woman near sink in bathroom

Dehydration can cause stomach upset, including nausea and vomiting. Throwing up eliminates more fluids from the body, which can make dehydration worse.

On the flipside, an illness that causes vomiting and diarrhea can itself result in dehydration. This is the most common cause of dehydration in children.


Your Mouth May Be Dry

woman with dry mouth

A dry mouth can be one of the first signs of dehydration.


You Get a Headache

woman with headache holds hand to her temple making a painful expression

When you're dehydrated, the brain loses fluid, causing it to shrink and pull away from the skull. That tension can can cause a headache (one of the reasons why it's a common symptom of a hangover; alcohol dehydrates you). Dehydration can also trigger migraines. 


You Become Constipated

Woman with prostate problem in front of toilet bowl. Lady with hands holding her crotch, People wants to pee - urinary incontinence concept

Plenty of fluids are necessary to keep your digestive tract running smoothly, and when you're dehydrated, your bowels may move less frequently or not at all, causing stomach discomfort.

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You Have Bad Breath

Woman checking her breath with hand

Dehydration can cause a lack of saliva, causing an increase in bacteria throughout your mouth. The result: Stinky breath.


You May Stop Sweating

Stressed woman drying sweat using a wipe in a warm summer day in a park

With body fluids depleted, you may stop sweating and your skin may feel dry. This is a symptom that dehydration is severe. Without sweating, the body can no longer cool itself and will continue to overheat.


Your Heart Rate May Rise

Woman having heart attack at home

When there's less water in your body, the amount of circulating blood decreases and the blood itself thickens. That means the heart has to work harder to pump blood everywhere it needs to go. That can cause a rapid heartbeat or palpitations. If 


You May Feel Confused

Portrait of stressed mature woman with hand on head looking down. Worried woman wearing spectacles. Tired lady having headache sitting indoors.

Another symptom of severe dehydration, confusion or hallucinations can result from less blood or oxygen reaching the brain. This symptom warrants immediate medical attention. 


You May Go Into Shock

Young woman, blond hair, fainted in bed.

Heat stroke—a condition that results when your body overheats—can cause your blood pressure to drop to dangerously low levels, leading to shock, which can be fatal. 

Avoid heat stroke and dehydration by drinking plenty of water, especially during warmer weather. Experts advise drinking five to seven cups a day, and you may need more when it's hot or you're physically active. Sip water throughout the day—remember, don't wait until you become thirsty.

As for our current pandemic: To get through it at your healthiest, don't miss these 37 Places You're Most Likely to Catch Coronavirus.


Michael Martin
Michael Martin is a New York City-based writer and editor. Read more about Michael
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