Conditions · Pediatrics and neonatology
Dehydration in children (acute diarrhoeal disease) !
Children with diarrhoea or vomiting lose water and salts fast. Grading how dry they are guides oral rehydration or, if severe, IV fluids.
Updated 2026-11-01
Structures involved
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In the clinical exam
- Hydration status: signs of dehydration
- Capillary refill time
- Vital signs in children: how they change with age
- Dehydration and fluid overload
Why it happens
- Shock: types, stages and the organs it damages
- Severe acute malnutrition: marasmus and kwashiorkor
- Water and electrolyte absorption and how diarrhea happens
- Dehydration and fluid overload
- Body fluid compartments
What it is
Loss of body water and electrolytes in a child, most often from acute diarrhoea with or without vomiting. Its severity is graded at the bedside (no, some or severe dehydration), and the grade decides the rehydration plan (A, B or C in the WHO/AIEPI strategy).
Who gets it
Acute diarrhoeal disease remains a leading cause of death in children under five worldwide, and most of those deaths come from dehydration. In Colombia and Latin America it is a frequent reason for consultation, with more risk where safe water, sanitation or vaccination against rotavirus are lacking, and in malnourished children. The AIEPI (IMCI) strategy is the national framework for assessing and treating it in primary care.
Causes
- Viral gastroenteritis, mainly rotavirus and norovirus
- Bacterial infection (e.g. diarrhoeagenic Escherichia coli, Shigella, Salmonella, Campylobacter, Vibrio cholerae)
- Parasites such as Giardia and Cryptosporidium
- Extra losses from vomiting, fever and fast breathing, with poor oral intake
Risk factors
- Age under one year (higher body water turnover and surface area)
- Malnutrition and low birth weight
- No access to safe water, poor sanitation and hygiene
- Not exclusively breastfed in the first six months
- Incomplete vaccination (rotavirus, measles)
- Inability to drink or persistent vomiting
Pathophysiology
Infection of the small-bowel mucosa causes secretion of chloride and water into the lumen and reduced absorption, so stool losses exceed intake. Extracellular volume falls first, lowering perfusion of skin, kidneys and brain; the kidney retains sodium and water and urine output drops. Uncorrected losses lead to hypovolaemic shock, metabolic acidosis from bicarbonate loss and poor perfusion, and sodium or potassium disturbances. Oral rehydration works because sodium–glucose co-transport in the jejunum stays intact and pulls water with it.
Classification
- No dehydration: not enough signs for the other grades (Plan A, home fluids)
- Some dehydration: two or more of restlessness or irritability, sunken eyes, drinking eagerly, skin pinch going back slowly (Plan B, supervised oral rehydration)
- Severe dehydration: two or more of lethargy or unconsciousness, sunken eyes, unable to drink or drinking poorly, skin pinch going back very slowly (Plan C, intravenous fluids)
- By sodium: isonatraemic (most common), hyponatraemic or hypernatraemic
Symptoms and signs
- Diarrhoea, often with vomiting and fever
- Thirst and eager drinking in moderate dehydration
- Dry mouth and tongue, no tears when crying
- Sunken eyes and, in infants, a sunken anterior fontanelle
- Fewer wet nappies or dark, scant urine
- Restlessness and irritability, progressing to lethargy
- Skin pinch that returns slowly; cool extremities and prolonged capillary refill when severe
Diagnosis
- Clinical
- Bedside grading with the AIEPI/WHO signs: general condition, eyes, thirst and ability to drink, and skin pinch, plus capillary refill, pulse, fontanelle, urine output and weight (acute weight loss estimates the deficit). Look for blood in the stool, malnutrition and other infections.
- Tests
- Not needed for no or some dehydration. In severe dehydration, IV therapy or an unclear picture: serum sodium, potassium, glucose, bicarbonate or blood gas, urea and creatinine. Stool tests only for dysentery, outbreaks or persistent diarrhoea.
- Imaging
- Not needed. Abdominal ultrasound or X-ray only if a surgical cause (intussusception, obstruction, appendicitis) is suspected.
Differential diagnosis
- Surgical abdomen: intussusception, appendicitis or bowel obstruction
- Sepsis, meningitis or urinary tract infection presenting with vomiting
- Diabetic ketoacidosis
- Dengue with plasma leakage
- Adrenal insufficiency or salt-wasting congenital adrenal hyperplasia in infants
Goal of treatment
Replace the existing deficit, keep up with ongoing stool losses and continue feeding, using the oral route whenever possible and intravenous fluids only for severe dehydration or failure of oral rehydration.
Treatment
- Acute
- Plan A (no dehydration): extra fluids and oral rehydration solution at home after each loose stool, continued breastfeeding and usual diet, zinc, and teaching caregivers the danger signs.
- Medical
- Plan B (some dehydration): low-osmolarity oral rehydration solution given in small, frequent sips over about four hours under supervision, then reassessment; nasogastric rehydration if the child cannot drink but is not in shock.
- Acute
- Plan C (severe dehydration or shock): rapid intravenous isotonic crystalloid (lactated Ringer's or normal saline) in boluses, reassessing after each, then oral solution as soon as the child can drink.
- Medical
- Zinc supplements for 10 to 14 days shorten and lessen the episode; antibiotics only for dysentery or suspected cholera; antidiarrhoeal and antimotility drugs are not used in children; antiemetics such as ondansetron may help oral intake in selected cases.
- Follow-up
- Nursing priorities: weight on admission and daily, intake and output (nappy weights), vital signs and capillary refill, level of consciousness, skin and mucosa, IV site, electrolytes when on IV fluids, and caregiver teaching on oral solution preparation and hand hygiene.
Complications
- Hypovolaemic shock and death
- Acute kidney injury (prerenal)
- Hypernatraemia or hyponatraemia, with seizures; cerebral oedema if hypernatraemia is corrected too fast
- Hypokalaemia and metabolic acidosis
- Malnutrition and growth faltering with repeated episodes
Prognosis
With timely oral or intravenous rehydration almost all children recover within days. Deaths concentrate in infants, malnourished children and those reaching care late or in shock.
Prevention
- Exclusive breastfeeding for six months
- Rotavirus and measles vaccination
- Safe drinking water, sanitation and handwashing with soap
- Early home oral rehydration at the start of diarrhoea
Test yourself
Think of the answer, then tap the question to see it.
Which signs define severe dehydration in the WHO/AIEPI grading?
Two or more of: lethargy or unconsciousness, sunken eyes, unable to drink or drinking poorly, and a skin pinch that goes back very slowly.
Which plan is used for a child with some dehydration?
Plan B: supervised oral rehydration solution over about four hours, then reassessment.
Why does oral rehydration solution work even during secretory diarrhoea?
Sodium–glucose co-transport in the small-bowel mucosa stays intact, so glucose carries sodium and water back into the body.
Which micronutrient is given with oral rehydration to shorten acute diarrhoea in children?
Zinc, for 10 to 14 days.
What is the main risk of correcting hypernatraemic dehydration too quickly?
Cerebral oedema with seizures.
Related conditions
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Diarrhoeal disease (World Health Organization, 2024); Dehydration: MedlinePlus Medical Encyclopedia (MedlinePlus (U.S. National Library of Medicine), 2024).
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