Signs and Symptoms of Dehydration

Dehydration occurs when your body doesn't have the amount of water it needs to function efficiently. You may become dehydrated after losing too much water or not adequately replacing lost water. Sweating, having diarrhea, and vomiting are examples of situations that can lead to dehydration.

When dehydrated, you may feel thirsty, have a dry mouth, and be fatigued. As dehydration progresses, the symptoms become more severe. Being able to recognize the symptoms of dehydration is key so that you know if you or a loved one is in need of fluid.

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Common Symptoms

While dehydration is uncommon among adults without any underlying health condition and who have access to water, anyone can become dehydrated. Dehydration is more likely among older adults, people who work or exercise in the heat, and those who have conditions or take medications that cause more sweat or urination.

When you are dehydrated, the symptoms you experience reflect how severe your dehydration is. The most common symptoms of dehydration are:

  • Thirst
  • Fatigue
  • Dry lips and skin
  • Decreased urine output 
  • Dark-colored urine
  • Headache
  • Muscle cramps
  • Lightheadedness, dizziness, or fainting
  • Low blood pressure upon standing
  • Palpitations

Mild to Moderate Dehydration Symptoms

Signs you are mildly to moderately dehydrated include: 

  • Thirst
  • Fatigue
  • Dry mouth or tongue
  • Decreased urine output or darker yellow urine
  • Dry skin
  • Headache
  • Lightheadedness, dizziness, or fainting
  • Inability to focus
  • Muscle weakness or cramps
  • Increased heart rate
  • Quickened breathing

Research has shown that many people don't recognize some of the less common symptoms, such as the inability to focus or muscle weakness, as signs of dehydration. As a result, people may not act on the symptoms by increasing their fluid intake.

Fast breathing is another symptom people do not usually associate with dehydration. Not only is it a sign of dehydration, but it can also worsen dehydration since respiration is one way your body loses water. 

Recognizing all symptoms of dehydration—particularly if you are at increased risk of dehydration—can prevent your dehydration from becoming severe. As soon as you recognize you are dehydrated, you can drink fluids, which is often all that's needed to treat dehydration that isn't severe.

Severe Dehydration Symptoms

Symptoms of severe dehydration may include:

  • Parched mouth
  • Dry, cracked lips
  • Low blood pressure
  • Lethargy
  • Reduced alertness
  • Lack of urination or urine that is very dark yellow or amber in color
  • Very dry skin that doesn't spring back quickly when pinched up (tented skin)
  • Sunken eyes
  • Confusion or loss of consciousness

One of the other signs of severe dehydration is slow capillary refill. When you press the tips of the fingers or toes and you are severely dehydrated, the color be slow to return. This slowed return to color could indicate decreased blood flow to the extremities and could be a sign of shock (when there is not enough blood flow in the body).

If your internal organs are not receiving adequate blood flow, you may develop complications like liver injuries, kidney failure, or electrolyte imbalances.

If you or a loved one is experiencing any sign or symptom of severe dehydration, you should seek medical help. Someone who is severely dehydrated may need intravenous fluids at a hospital to get hydrated and prevent serious complications.

Without treatment, severe dehydration can lead to permanent brain damage, seizure, or death.

Symptoms of Dehydration in Children

Infants and young children can become dehydrated more quickly than healthy adults.
The younger age groups are also more likely to become dehydrated in the first place because they vomit and have diarrhea more often.

Since infants and very young children cannot express thirst or other symptoms, be on
the lookout for these signs of dehydration:

  • No wet diaper for more than three hours
  • Unusual sleepiness or drowsiness
  • No tear production when crying
  • Sunken eyes
  • High fever
  • Irritability
  • Increased heart rate
  • Quickened breathing
  • The soft spots on the baby's head are sunken

When to See a Healthcare Provider

Severe dehydration can be life-threatening. Call for medical help immediately if you see someone experiencing or you yourself are experience any of these symptoms:

  • Confusion
  • Fainting
  • No urination
  • Fast heart rate
  • Fast breathing

Also get immediate medical help if you or a loved one is experiencing signs of shock, such as:

  • Low blood pressure
  • Loss of consciousness
  • Cold, clammy extremities
  • Pale or bluish skin and nails

A Quick Review

Mild dehydration can happen to anyone at any age. Thirst, dry mouth, and fatigue are some of the most common symptoms of dehydration and may indicate that you need to drink more fluids. The symptoms you experience depend on whether your dehydration is mild, moderate, or severe. If mild-to-moderate dehydration symptoms such as decreased urine output and dry skin are not recognized, the condition can progress and cause worsened symptoms such as no urine output and confusion. Most times, dehydration is mild and is reversed at home. When severe dehydration does occur, it's important to seek medical help so you can get the treatment you need and prevent any serious complications.

Frequently Asked Questions

  • Can dehydration hospitalize you?

    If dehydration progresses far enough, you may need medical help. You may need to stay in the hospital for a day or so as they stabilize you and get your fluids and electrolytes back to safe levels.

  • How does the ER rehydrate you?

    For adults, the ER staff will treat your dehydration by quickly replacing your fluids through an IV (intravenous line). They will also figure out what's causing your dehydration and address that if needed. For children, the rate of fluid replacement is based on how severe the dehydration is and how much the child weighs.

  • How do I know if I need IV fluids?

    You may need IV fluids with salt at a hospital if you have severe dehydration. A healthcare provider will determine whether you need this level of treatment. 

  • What happens when you are dangerously dehydrated?

    If you are experiencing symptoms of severe dehydration, you should seek immediate medical help. Not treating severe dehydration can make it so that you are not getting enough blood flow throughout your body. This can lead to serious complications, such as seizure.

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