Dehydration

 

Dehydration: Overview, Symptoms, Causes, and Prevention

Overview

Dehydration occurs when your body loses more fluids than it takes in, and it doesn’t have enough water to carry out normal functions. If lost fluids are not replaced, dehydration will occur.
Anyone can become dehydrated, but it is most dangerous for young children and older adults.

In children, severe diarrhea and vomiting are the most common causes. Older adults naturally have less water in their bodies and may have health conditions or take medications that increase the risk of dehydration. Even mild illnesses, such as lung or bladder infections, can cause dehydration in older adults.

Dehydration can also happen to anyone, especially in hot weather or during intense exercise if water intake is not sufficient.
Mild dehydration can often be treated by drinking fluids, but severe dehydration requires immediate medical attention.

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Symptoms

Thirst isn’t always an early sign of dehydration. Many people—especially the elderly—don’t feel thirsty until they are already dehydrated. It’s important to increase fluid intake in hot weather or when you’re ill.
Symptoms vary depending on age.

In Infants and Young Children

• Dry mouth and tongue

• No tears when crying

• No wet diapers for 3 hours

• Sunken eyes and cheeks

• Sunken soft spot on the head (fontanelle)

• Fatigue or irritability

In Adults

• Intense thirst

• Decreased urination

• Dark-colored urine

• Fatigue and weakness

• Dizziness or confusion

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When to See a Doctor

Contact your doctor if you or someone you care for:

• Has diarrhea lasting more than 24 hours

• Feels unusually sleepy, disoriented, or less active

• Cannot keep fluids down due to vomiting

• Has bloody or black stools

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Causes

Dehydration can occur simply from not drinking enough fluids due to illness, being busy, or lack of access to clean water while traveling or camping.
Other common causes include:

• Diarrhea and vomiting: Sudden, severe diarrhea can cause rapid loss of water and electrolytes. Vomiting worsens this loss.

• Fever: The higher your fever, the more fluids you lose.

• Excessive sweating: Intense physical activity in hot, humid weather increases fluid loss through sweat.

• Increased urination: This may result from uncontrolled diabetes or certain medications, like diuretics and some blood pressure drugs.

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Risk Factors

Anyone can become dehydrated, but certain groups are at higher risk:

• Infants and children: They lose fluids quickly through severe vomiting, diarrhea, or fever and may be unable to express thirst.

• Older adults: They have less body water, a reduced thirst response, and may take medications or have illnesses that increase dehydration risk.

• People with chronic illnesses: Conditions like diabetes or kidney disease increase dehydration risk. Even mild illnesses like colds or sore throats can make you drink less.

• Athletes and outdoor workers: Heavy sweating in hot or humid weather increases fluid loss, which can lead to heat-related illnesses.

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Complications

If untreated, dehydration can lead to serious health problems, including:

• Heat injury: Ranging from mild heat cramps to life-threatening heatstroke.

• Urinary and kidney problems: Including urinary tract infections, kidney stones, or kidney failure.

• Seizures: Caused by electrolyte imbalance affecting nerve signals.

• Hypovolemic shock: A severe and potentially fatal drop in blood pressure due to low blood volume.

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Prevention

The best way to prevent dehydration is to drink plenty of fluids and eat foods rich in water—such as fruits and vegetables.
Let thirst guide your daily fluid intake if you’re healthy, but drink more in certain conditions:

• Vomiting or diarrhea: Start rehydration early with water or oral rehydration solutions.

• Heavy exercise: Stay hydrated before, during, and after workouts.

• Hot or cold weather: Drink more in hot, humid conditions and also in cold, dry environments to counter moisture loss.

• Illness: Drink extra fluids when sick with fever, cold, or respiratory infections.