Summary

Acute dehydration in children occurs when the body loses more fluid than it takes in, leading to a deficit in total body water. Think of your child's body as needing a constant supply of water to function—when fluid losses (from vomiting, diarrhea, fever, reduced intake) exceed fluid intake, the body becomes dehydrated, affecting all organ systems. Dehydration is very common in children, especially infants and young children, who have a higher proportion of body water and are more vulnerable to fluid losses. The most common causes are gastroenteritis (vomiting and diarrhea), fever, and reduced fluid intake. The severity ranges from mild (minimal symptoms) to severe (shock, organ failure). The key to management is recognizing the severity (using clinical signs—skin turgor, capillary refill, mucous membranes, fontanelle in infants, eyes), providing appropriate rehydration (oral rehydration solution for mild-moderate, IV fluids for severe or unable to take oral), treating the underlying cause, and monitoring for complications. Most children recover well with appropriate rehydration, but severe dehydration can be life-threatening if not treated promptly.

Key Facts

• Definition: Deficit in total body water due to losses exceeding intake
• Incidence: Very common (millions of cases/year worldwide)
• Mortality: Very low (<0.1%) unless severe and untreated
• Peak age: Infants and young children (highest risk)
• Critical feature: Fluid losses exceeding intake, clinical signs of dehydration
• Key investigation: Clinical assessment (usually sufficient)
• First-line treatment: Oral rehydration (mild-moderate), IV fluids (severe or unable to take oral)

Clinical Pearls

"Clinical assessment is key" — The severity of dehydration is assessed clinically (skin turgor, capillary refill, mucous membranes, fontanelle, eyes). Don't rely on weight alone—clinical signs are more important.

"Oral rehydration works for most" — Most children with mild-moderate dehydration can be rehydrated orally with oral rehydration solution (ORS). IV fluids are only needed for severe dehydration or if unable to take oral fluids.

"Infants are more vulnerable" — Infants have a higher proportion of body water and are more vulnerable to dehydration. Have a lower threshold for concern in infants.

"Treat the cause" — Always treat the underlying cause (gastroenteritis, fever, etc.) while rehydrating. Rehydration alone isn't enough if the cause isn't addressed.

Why This Matters Clinically

Dehydration is very common in children and can be life-threatening if severe and not treated promptly. Early recognition (especially in infants where signs may be subtle), appropriate rehydration (oral for most, IV for severe), and treating the underlying cause are essential. This is a condition that all clinicians caring for children need to recognize and manage, as it's very common and usually easily treated.

Structured Approach: ABCDE

A - Airway

• Assessment: Usually patent
• Action: Secure if compromised

B - Breathing

• Look: Usually normal (may have tachypnea if severe)
• Listen: Usually normal
• Measure: SpO2 (usually normal)
• Action: Support if needed

C - Circulation

• Look: Poor perfusion (mottled, cold), signs of shock
• Feel: Pulse (may be fast, weak), BP (may be low), capillary refill (slow)
• Listen: Heart sounds (usually normal)
• Measure: BP (may be low), HR (may be high)
• Action: IV fluids urgently if severe

D - Disability

• Assessment: Mental status (may be altered if severe)
• Action: Assess if severe

E - Exposure

• Look: Full examination, assess dehydration signs
• Feel: Skin turgor, fontanelle (infants)
• Action: Complete examination, assess severity

Specific Examination Findings

Dehydration Assessment (Critical):

Weight (If Available):

• Comparison: Compare to recent weight
• Loss: Weight loss indicates fluid deficit
• Action: Helps assess severity

Special Tests

Natural History (Without Treatment)

Untreated Dehydration:

• Mild: Usually resolves (if able to drink)
• Moderate: May progress to severe
• Severe: High risk of shock, organ failure, death

Outcomes with Treatment

Factors Affecting Outcomes:

Good Prognosis:

• Early treatment: Better outcomes
• Mild-moderate: Usually recover quickly
• Able to take oral: Usually recover quickly
• No complications: Better outcomes

Poor Prognosis:

• Delayed treatment: Higher risk of complications
• Severe dehydration: Longer recovery, more complications
• Shock: More serious, needs ICU
• Very young: May have worse outcomes

Prognostic Factors

Key Guidelines

1. WHO Guidelines (2005) — The treatment of diarrhoea: a manual for physicians and other senior health workers. World Health Organization

Key Recommendations:

• Oral rehydration for mild-moderate
• IV fluids for severe
• Evidence Level: 1A

2. NICE Guidelines (2009) — Diarrhoea and vomiting caused by gastroenteritis: diagnosis, assessment and management in children younger than 5 years. National Institute for Health and Care Excellence

Key Recommendations:

• Similar to WHO
• Evidence Level: 1A

Landmark Trials

Multiple studies on oral rehydration, IV fluids.

Evidence Strength

What is Dehydration?

Dehydration happens when your child's body loses more fluid than it takes in, leading to a deficit in total body water. Think of your child's body as needing a constant supply of water to function—when fluid losses (from vomiting, diarrhea, fever, or not drinking enough) exceed fluid intake, the body becomes dehydrated.

In simple terms: Your child's body doesn't have enough water. This is usually easy to fix by giving your child fluids, but if severe, it can be serious and needs urgent treatment.

Why does it matter?

Dehydration is very common in children and can be serious if severe and not treated. Early recognition and appropriate rehydration (giving fluids) are essential. The good news? Most children recover quickly with appropriate rehydration.

Think of it like this: It's like your child's body running low on water—with the right fluids, it usually recovers quickly.

How is it treated?

1. Assess How Severe:

• Your doctor will check: Your child's skin, mouth, eyes, and other signs to see how dehydrated they are
• Why: To decide the best way to rehydrate

2. Give Fluids:

• If mild-moderate: Your child will drink special rehydration solution (ORS) - small, frequent sips
• If severe or can't drink: Your child will get fluids through a drip (IV fluids)
• Why: To replace the lost fluid

3. Treat the Cause:

• If gastroenteritis: Supportive care
• If fever: Medicine to reduce fever
• If other causes: Treated as appropriate
• Why: To stop the fluid losses

4. Monitor:

• Your doctor will watch: To make sure your child is improving
• Reassess: To see if more treatment is needed

The goal: Replace the lost fluid and treat whatever's causing the fluid losses.

What to expect

Recovery:

• Mild cases: Usually recover within hours with oral fluids
• Moderate cases: Usually recover within hours to a day with oral or IV fluids
• Severe cases: Usually recover within days with IV fluids

After Treatment:

• Fluids: Your child will continue to need fluids (oral or IV) until rehydrated
• Monitoring: Your doctor will monitor to make sure your child is improving
• Going home: When your child is stable and able to take fluids

Recovery Time:

• Mild cases: Usually hours
• Moderate cases: Usually hours to a day
• Severe cases: Usually days

When to seek help

See your doctor if:

• Your child is not drinking well
• Your child has vomiting or diarrhea and seems dehydrated
• Your child has a fever and seems dehydrated
• Your child's mouth is dry, or they're not making tears
• You're concerned about your child

Call 999 (or your emergency number) immediately if:

• Your child is very unwell
• Your child is confused or not responding normally
• Your child's skin is mottled or cold
• Your child is in shock
• You're very worried about your child

Remember: If your child is not drinking well, especially if they have vomiting, diarrhea, or a fever, see your doctor. Dehydration is usually easy to fix, but if severe, it needs urgent treatment. Trust your instincts—if you're worried, seek help.