What are the symptoms of dehydration?

Symptoms of dehydration include the following:

  • Bad breath. People's breath may be telling them that their body is running extremely low on water content. Saliva has antibacterial properties in it, but lack of hydration can deter the body from producing enough of it. In most cases, the cause for bad breath is dehydration.
  • Extra yellow urine. Sounds gross, right? But it's true. Unfortunately, thirst is not the only parameter to know if the body is crying out for water, especially in children and older adults. The color of urine is a better indicator. When people are properly hydrated, their urine should be pale yellow. Urine that is dark yellow (or even orange) or small in quantity is a telling sign of dehydration.
  • Headache and fatigue. When the body loses too much fluid, electrolytes like sodium and potassium are also lowered, altering the chemical makeup of the blood. As the brain is super-sensitive, it triggers a reaction in the form of a headache and fatigue. The more dehydrated a person becomes the more a headache grows and energy lessens.
  • Thirst. Seems like a no-brainer, of course, but thirst can actually occur fairly late in the process of dehydration. The key is to stay hydrated—thus avoiding thirst.

Trinity Health is a Catholic health care organization that acts in accordance with the Catholic tradition and does not condone or support all practices covered in this site. In case of emergency call 911. This site is educational and not a substitute for professional medical advice, always seek the advice of a qualified health care provider.

Without enough fluid coming in, your body starts to shut down and stops functioning properly. Severe dehydration is a serious condition, so it's best to prevent dehydration in the first place.

Early symptoms that you're in need of fluid include thirst, dry mouth and/or sticky, thick saliva. Pay attention to your body's warning signs and replenish your liquids and electrolytes with drinks that are designed to rehydrate. You can make your own rehydration drink or buy over-the-counter products, such as Pedialyte, Lytren or Rehydralyte.

Avoid sports drinks, such as Gatorade, Powerade and All Sport. Although they replenish fluids, sports drinks also contain a lot of sugar, which, if you have diarrhea, can make it worse.

See a health professional immediately if you have any of the following symptoms of dehydration:

  • Sunken eyes
  • Dry eyes or no tears
  • Nonelastic skin that doesn't return to place when pinched
  • Rapid breathing and/or rapid heartbeat
  • Listlessness
  • Little or no urine output for eight hours or more

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There are several signs of dehydration you should be looking out for including:

  • Thirst
  • Dry mouth
  • Decreased urine or urine is dark yellow/orange color.
  • Dizziness
  • Headache
  • Fever
  • Increased heart rate
  • Decreased blood pressure
  • Dry skin, lack of sweating
  • Constipation

Thirst alone is a poor indicator to determine if you’re thirsty. To avoid dehydration follow these guidelines:

  • Sedentary women and men should consume approximately 9 to 13 cups per day respectively.
  • Drink an additional 8 ounces of water for every 25 pounds you carry above your ideal weight.
  • Consume 2 to 3 cups of water two hours before exercise.
  • Drink 6 to 12 ounces of water for every 15 to 20 minutes of exercise.
Dr. Mehmet Oz, MD
Cardiologist (Heart Specialist)

Dehydration has many dangers. Look for the following symptoms:

  • Dark Urine. Your urine should be clear; if looks like tea when you go to the bathroom, you’re dehydrated.
  • Dry Skin. If your body is dehydrated, it will do everything it can to hold onto fluids. Your skin is the first place to be robbed of water. Major indicators of dehydration include skin that is less plump and flexible, sunken eyes, dark circles or dry lips. Assess your skin with a skin turgor test; pinch a fold of skin on top of your forearm. If this pinch and stays up in a tent, there is not enough water volume behind your skin.
  • Dizziness. When your body is dehydrated, it is harder to distribute water. Dizziness can occur when you go from lying down to sitting or standing. The upright movement causes water to rush away from your heart and brain, which makes you dizzy.
  • Constipation. Your body absorbs water from your intestines and draws moisture from your stool. This makes them hard, dry and difficult to pass.

Dehydration symptoms vary depending on the severity. Mild symptoms are by far the most common and may include thirst, headache, fatigue, decreased urine output and lightheadedness. More severe dehydration may cause dry skin with poor elasticity, fast heartbeat and shortness of breath. Very severe dehydration may cause confusion, unconsciousness and even death.

Dr. Carlos F. Lerner, MD

The signs and symptoms of dehydration vary with severity. Symptoms may include:

  • thirst
  • less-frequent urination
  • dry skin
  • dry mouth and tongue
  • fatigue
  • light-headedness
  • confusion
  • increased heart rate
  • increased breathing 

The symptoms of dehydration in young children are:

  • no tears when crying
  • no wet diapers for more than three hours
  • sunken abdomen, eyes or cheeks
  • skin that does not flatten when pinched and released
  • showing no interest in things (listlessness)
  • irritability

Dehydration is a very common heat-related condition. It can also be a dangerous consequence of diarrhea, vomiting and fever. In the most severe instances, dehydration can be life-threatening if untreated.

Dr. Aruna V. Josyula, MD
Geriatric Medicine Specialist

Dry mouth and dry throat can be signs of dehydration, but there are medications that can cause these symptoms as well. Feeling thirsty, weak, dizzy or confused can also be signs of dehydration. It is important to note that diabetes can also cause a person to feel thirsty, so it is best for patients to discuss all of their symptoms with their doctor. People with dehydration often feel like their heart is racing, or that they are having palpitations, which can also be a red flag. Fainting and decrease in urine output are of special concern.

Trinity Health is a Catholic health care organization that acts in accordance with the Catholic tradition and does not condone or support all practices covered in this site. In case of emergency call 911. This site is educational and not a substitute for professional medical advice, always seek the advice of a qualified healthcare provider.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.