Dehydration
Dehydration is the loss of more body water than is being replaced. It ranges from mild (easily corrected) to severe (life-threatening), and is especially dangerous in young children and older adults.
Quick Facts
- ICD-10: E86.0
- Most at risk: Children, older adults
- Hot weather: Major contributor
- Severe form: Medical emergency
When to Seek Emergency Care
- Confusion, extreme drowsiness, or fainting
- Rapid heartbeat or rapid breathing
- Inability to keep fluids down
- Very dark or no urine for 8+ hours (adults) or 6+ hours (infants)
- Sunken eyes; sunken soft spot in babies
- Cold or mottled hands and feet
Symptoms
Adults
- Thirst
- Dry mouth and lips
- Headache
- Dizziness, especially when standing
- Dark yellow urine; less frequent urination
- Fatigue
- Dry skin with reduced elasticity
Children and infants
- Few or no tears when crying
- Dry diaper for several hours
- Sunken eyes or soft spot
- Listlessness or irritability
Causes
- Diarrhea and vomiting
- Fever and sweating
- Excessive sweating (exercise, hot environments)
- Frequent urination (uncontrolled diabetes, diuretics)
- Reduced intake (illness, swallowing problems, lack of access)
- Burns or large skin losses
Risk Factors
- Infants and young children (more vulnerable to GI illness)
- Older adults (reduced thirst sensation, medications)
- Chronic illnesses (diabetes, kidney disease)
- Strenuous activity in heat
- High altitude
Diagnosis
Dehydration is usually diagnosed clinically. Tests may include:
- Blood tests (electrolytes, kidney function, BUN/creatinine ratio)
- Urine concentration testing
- Weight comparison in children
Treatment
Mild to moderate
- Sip fluids gradually — water, oral rehydration solutions, broth
- For children with diarrhea, oral rehydration solutions (ORS) are preferred to plain water or juices
- Avoid sugary drinks and caffeine if severe diarrhea
- Reintroduce normal foods when tolerated
Severe
- Intravenous fluids in a medical setting
- Electrolyte replacement
- Treatment of the underlying cause
Prevention
- Drink fluids regularly through the day, more in hot weather or with exercise
- Replace fluids during illness, even in small sips
- Encourage older adults to drink on schedule, not just when thirsty
- Monitor urine color — pale yellow generally suggests adequate hydration
When to See a Doctor
Seek care for any signs of severe dehydration, dehydration in young children or older adults, vomiting that prevents fluid intake, persistent diarrhea more than 2 days, or symptoms that worsen despite home rehydration.
Frequently Asked Questions
There is no single correct amount. A common reference is about 2–3 liters daily for adults, but needs vary with body size, activity, climate, and health conditions. Pale yellow urine suggests adequate intake.
Yes — excessive water without electrolytes can cause hyponatremia (low sodium), which is dangerous. This is most relevant for endurance athletes and people who drink very large volumes.
For most everyday activity, water is sufficient. For prolonged or intense exercise (over an hour), sports drinks help replace electrolytes lost in sweat.
Give small, frequent amounts of oral rehydration solution (ORS) — available at pharmacies. Plain water and sugary drinks alone don't replace the lost electrolytes adequately.
References
- Centers for Disease Control and Prevention. Oral Rehydration Solutions.
- Mayo Clinic. Dehydration — Symptoms and causes.