Signs You Are Dehydrated

Lake Oconee Health, Greensboro Nutritionist

Everyone has done it. You wake up late, rush to work skipping breakfast, next thing you know its lunchtime and all you have had to drink is your morning coffee—if that. So, since dinner, the night before until midday is around 17 hours and you’ve had a paltry cup of fluid that just so happens to be a diuretic.

You may be surprised to hear that an estimated 90 percent of Americans are walking around dehydrated.

Dehydration is defined as “a harmful reduction in the amount of water in the body.” 

Water is a vital nutrient and our body needs water to stay alive, and not having enough is harmful, even deadly.

We are over 60 percent water (two-thirds), our brain over 80 percent water. To put these numbers in perspective, a 70-kilogram adult (154 pounds) is about 42 Liters of water.

We need water in every single one of our 3 trillion cells, to utilize energy, chemical processes, and maintaining life. It is essential for us to breathe, think, our heart to pump blood to our cells, digest, and so on and so forth.

And, it influences 100 percent of the processes that take place: regulates temperature, lubricates joints, protects our brain and spinal cord, transports material, and gets rid of wastes to name a few. The ability of water to dissolve so many substances allows our cells to use valuable nutrients, minerals and chemicals in biological processes. In fact, to function properly, all the cells and organs of our body need water.

It is important to understand that being hydrated is vital/important/crucial, how much water intake we need daily, and what the signs and symptoms are of being dehydrated (what our body’s alarms are)

Dr. Nina’s What You Need to Know About Hydration and Dehydration

How much water do we need?

Every day, we lose or use about 2 quarts of water (approximately 8 cups or 2 Liters) through breathing, sweating, and digestion. At the very minimum we need to replenish that amount. And too little “in” or too much “out” can lead to dehydration: not drinking enough fluids; drinking fluids that are diuretics (cause you to urinate) such as soda, certain teas, or coffee; sweating too much from exercise or heat; or diarrhea or vomiting.

What happens when we do not get enough water?

Because it is essential to life, our body has a number of alarms that go off when “our well” is not properly filled. Even a small decrease of 1 or 2 percent can cause signs and symptoms. Let’s take for example a 70 kg (154 pound adult) who is about 42 Liters of water. Being just half a liter or one liter of water in the red, has ill-effects. 

Signs and Symptoms of dehydration

Feeling thirsty is an obvious clue that your body needs more water. However, children, older adults, and those who are chronically dehydrated, may have a decreased thirst sensation. And, too, the signs and symptoms can sometimes be subtle or non-specific (meaning can result from a number of conditions). Thus, it is important to listen to your body, always—and to know what to listen for.


Dehydrated skin lacks water and manifests as lips that are rough, flaking, cracked and red or skin that has visible fine lines or surface wrinkles, itches, appears dull, or uneven tone and complexion. And in cases when dehydration is severe, under-eye circles can appear or become more pronounced, eyes sunken, or shadows may appear around the nose.

Fatigue, lethargy, tiredness

Not sure why you just don’t have much energy? Research shows that even mild dehydration can make you feel tired even though you are well-rested. It is believed that this is due to the drop in blood pressure and, hence, blood flow to the brain. If your brain isn’t getting the right amount of oxygen and nutrients it needs, it will not function optimally.

Brain function

Our brain is quite a watery organ—eighty percent of it is water! It is no wonder that even mild dehydration can impair proper function such as thinking, memory, reaction time, concentration, balance, and temperature control. In one study, mild dehydration was shown to affect driving, including drifting across lanes and slowed reaction time while braking.

Heart effects 

Our heart pumps blood through our blood vessels to each and every single one of our body’s three trillion cells. Blood is mostly liquid, with the liquid being water that has salts, gases, nutrients, proteins, and red and white blood cells and platelets. And when we are dehydrated, the volume of blood in vessels is decreased, making it more concentrated and viscous. Our heart has to work harder to move viscous blood throughout our body. And, our vessels constrict to maintain a proper blood pressure, but that means the heart has to generate more force for every beat. And, too, our heart rate increases (more heart beats) to compensate for the decrease in blood volume, so the cells get what they need.

Headaches and migraines

Dehydration causes our brain to temporarily contract and pull away from the skull, causing our heads to ache. Additionally, dehydration is one of the most avoidable causes of migraines. In a study published in the journal Neurology, the frequency of migraines jumps almost 8 percent for every 9-degree rise in temperature. In addition to brain volume contraction, it is believed that the loss of electrolytes that results when we are dehydrated causes nerves in the brain to produce pain signals.

Bad breath

Our saliva moistens our food and also has an antibacterial effect. But not drinking enough water can equate to less saliva. And, when our mouth becomes dry, it is easier for bacteria to settle in, leading to the bad odor seen with bad breath.

Hunger and sugar cravings

We are unable to properly break down fuel stored in our liver when there is not enough water. Our body goes into panic mode and signals are sent to “Eat!” so we can get the fuel we need. Often, we crave for sugary foods to provide quick fuel. So the next time you feel hungry or have a sweet tooth, drink a cup or two of water first. You may not actually be hungry.   


Not having enough water in our bodies can make our stool more solid and decrease transit through our gut. This is because water gets soaked up in the large intestines, as our body attempts to tap into any available source.


Dehydration elicits a stress response from our body, that there is a danger, and we need to do something about it. The body’s stress response is accompanied by anxious thoughts, worry, and fear so that the mind can coordinate with our body and help us to fight or flee a situation. Additionally, an increase in heart rate can, in and of itself, make us feel anxious.

How can I prevent dehydration?

Drink enough water! Most adults need approximately 2 liters of water a day (those with kidney and heart failure may need less and it is always important to speak with your doctor when you have a question) While it can require an adjustment period to get up to speed, it is feasible and there are numerous benefits. Some tips include:

  • Track how much water you drink on a notepad, phone app, or journal
  • Drink a glass of water first thing in the morning
  • Drink a glass of water before every meal, with the added benefit that it can decrease how much food and, hence, calories you consume
  • Carry a water bottle with you to help you meet your quota
  • Drink a glass of water before exercising
  • If you had an increase sweat session from heat or working out, make sure to drink a few extra glasses. Not sure if you had enough? Look at your urine. Light, straw colored urine is usually a good sign that you are hydrated
  • Reach for water instead of soda or other flavored drink. If you drink coffee or tea, make sure to also drink an equivalent amount of water to combat the diuretic effect. 
  • Flavor your water with fruit, lemon, lime, or cucumbers to add some zing
  • Add fruit and veggies with a high water content such as cucumbers, zucchini or watermelon
Author Profile

Dr. Nina Radcliff is dedicated to her profession, her patients and her community, at large. She is passionate about sharing truths for healthy, balanced living as well as wise preventive health measures.

She completed medical school and residency training at UCLA and has served on the medical faculty at The University of Pennsylvania. She is a Board Certified Anesthesiologist. Author of more than 200 textbook chapters, research articles, medical opinions and reviews; she is often called upon by media to speak on medical, fitness, nutrition, and healthy lifestyle topics impacting our lives, today.