Author: Richard Freeman / Editor: Claire Onyon / Reviewer: Thomas MacMahon, Richard Freeman / Codes: GC3, GC5, SLO5Published: 09/07/2021



Paediatric gastroenteritis is common and results in a significant number of presentations to the emergency department (ED).

It is essential to employ an evidence-based approach in the assessment and management of these children, based upon national guidance, to resuscitate appropriately, treat where indicated, and discharge safely, avoiding unnecessary admissions.


Diarrhoea and vomiting have historically had various definitions depending upon the author. NICE has standardised the definition in their current guidance [1]. Table 1: Definitions of vomiting and diarrhoea according to NICE [1].

Vomiting A forceful ejection of stomach contents up to and out of the mouth (as distinct from regurgitation commonly seen in infants)
Diarrhoea Passage of liquid or watery stools. In most cases there is an associated increase in frequency and volume

Gastroenteritis should therefore be suspected in children if there is a sudden onset of diarrhoea, with or without vomiting.


Across Europe, the incidence of acute gastroenteritis ranges from 0.5 to 1.9 episodes per person per year, with a higher risk for younger children [2]. In 2006, approximately 10% of the 23 million European children under five presented to healthcare services with gastroenteritis [3], which made up 16% of paediatric ED workload [4], mainly during the winter months. Hospitalisation rates varied, but over 77,000 were admitted for treatment across Europe annually [5].

With the licensing of rotavirus vaccines, this picture has changed. In countries with good vaccine uptake, a 65% to 84% reduction in hospitalisation for rotavirus gastroenteritis has been achieved [6].

Spread of the causative organism is usually via the faecal-oral route. Most transmission occurs in the community, but nosocomial infection also occurs [7].

Causative Organisms


  • Rotavirus was by far the most common pathogen causing gastroenteritis in children (estimated to cause up to 60% of all cases [3, 8] in countries without vaccination).
  • Norovirus is now the leading cause in countries where rotavirus vaccination is established
  • Adenovirus, astrovirus, and calicivirus may also be responsible.

Bacteria / protozoa

  • Campylobacter and salmonella species, and protozoal infections such as cryptosporidium may also cause gastroenteritis.

It is not necessary to identify a pathogen in the vast majority of cases; hence routine stool cultures are not required.

Initial Assessment

The priorities in the initial assessment include:

  1. Could something else be causing these symptoms?
  2. Does this child have risk factors for a more serious clinical course?
  3. Are there any red flags that this child is very unwell / needs resuscitation?
  4. How dehydrated is this child?

In your history and examination, any of the following features should prompt you to consider an alternative diagnosis [1]:

  • fever:
    • temperature of 38°C or higher in children younger than 3 months
    • temperature of 39°C or higher in children aged 3 months or older
  • shortness of breath or tachypnoea
  • altered consciousness
  • neck stiffness
  • bulging fontanelle in infants
  • non-blanching rash
  • blood and/or mucus in stool
  • bilious (green) vomit
  • severe or localised abdominal pain
  • abdominal distension or rebound tenderness
  • vomiting lasting more than 24 hours without diarrhoea
  • persistent diarrhoea (more than 10 days)

These alternative causes include:

  • Other infections: meningitis, septicaemia, urinary tract infection, pneumonia
  • Acute surgical abdominal conditions: appendicitis, volvulus, intussusception
  • Non-infective gastroenterological conditions: inflammatory bowel, coeliac disease, malabsorption, overflow constipation
  • Antibiotic associated diarrhoea: including Clostridium Difficile

Risk Stratification

The following children are at increased risk of dehydration [9-11]:

  • Young age (<1 year of age and especially < 6 months)
  • Infants who were of low birth weight
  • Those with signs of malnutrition
  • Frequent symptoms (>5 diarrhoeal stools or >2 vomits within the previous 24 hours)
  • Those who are not offered supplementary fluids or stopped breastfeeding prior to presentation

Be more cautious with these children before considering discharge.

Red Flags

Current best practice is to stratify the degree of dehydration into minimal, mild to moderate, and severe based on the overall clinical picture of the child. These roughly correspond to the NICE categories of “Not clinically detectable”, “Clinical dehydration” and “Clinical shock” [1].

Evidence has shown that prolonged capillary refill time (CRT), abnormal skin tone and respiratory pattern are important signs and significantly associated with the degree of dehydration [12], but there is poor agreement between clinicians in estimating the presence of these signs.

‘Red flags’ may help to identify those at risk of progression to shock.

Table 2: Symptoms and signs of clinical dehydration and shock [1]

Assessment of Dehydration

Your initial clinical assessment will stratify the child into minimal, mild to moderate, or severe dehydration (see Table 2) [1, 2]. This translates roughly into <5% loss in body weight, 5-10% loss of body weight and >10% loss of body weight and is essential for guiding treatment.

Scoring systems exist, but have not been adequately validated in clinical settings.

Consider also if hypernatraemic dehydration could be present (Na+ >145mmol/L). It is rare during gastroenteritis, with a frequency of <4% of all cases [2], but should be suspected if:

  • Child <6 months old
  • “Doughy” skin
  • Tachypnoea
  • Jitteriness

Other neurological signs: increased muscle tone, hyperreflexia, convulsions, drowsiness, coma.

Stool Culture

The majority of cases of paediatric gastroenteritis are viral, and even cases of bacterial or protozoal infection, are generally self-limiting.

Stool cultures should not be sent routinely.

Consider sending a stool sample for microscopy, culture and sensitivity (MC&S) if [1, 2]:

  • The child has recently been abroad to an at-risk area
  • The diarrhoea has not improved by day 7
  • There is uncertainty regarding the diagnosis

A sample should be sent if:

  • Septicaemia is suspected
  • There is blood and/or mucus in the stool
  • The child is immunocompromised

In the case of an outbreak, notify and act on the advice of the public health authorities as to what samples should be sent.

Laboratory Measures

There is a lack of good quality evidence for the use of laboratory measures in the assessment of dehydration [12] and in differentiating between viral and bacterial aetiology [1].

Blood biochemistry should not be carried out routinely.

Consider measuring laboratory U&Es, venous blood gas and blood glucose if:

  • Starting intravenous rehydration
  • Hypernatraemic dehydration is suspected
  • The child is severely dehydrated / clinically shocked

The child is mild to moderately dehydrated but the examination findings are not consistent with gastroenteritis as the cause.

General Management

The aim of treatment is to replace fluid and electrolytes. Most children with gastroenteritis can be safely managed at home with advice and support from a healthcare professional if necessary [1].

The main questions to consider in each case are:

  1. Does this child need immediate resuscitation?
  2. What way should I give replacement fluids?
  3. What fluid should I use?
  4. How much fluid should I give, and how quickly?
  5. Should I give any other treatment in addition to fluids?
  6. Which children are safe to let home, and what should I tell their parents?

Choice of fluid replacement route

Oral rehydration is generally the first-line treatment for all children with acute gastroenteritis who are not clinically shocked. For every 25 children (95% CI 14 to 100) treated with oral rehydration, it is estimated one would fail and require IV rehydration [13]. It is less invasive than IV rehydration with no evidence of any important clinical difference [14].

Where oral rehydration is not feasible, nasogastric fluid replacement is preferred ahead of IV rehydration [2], though local practice may vary.

IV rehydration is required in cases of shock; dehydration with altered level of consciousness; worsening of dehydration or lack of improvement despite attempts at oral rehydration; persistent vomiting despite appropriate fluid administration; and severe abdominal distension and ileus [2].

Choice of fluid

For oral or NG rehydration, reduced osmolarity oral rehydration solution (ORS) is recommended (50/60mmol/L of sodium) [2]. Lemonade, sports drinks or homemade ORS are not appropriate.

For IV rehydration, during the initial phase of restoring fluid volume, isotonic fluid (usually 0.9% NaCl) is recommended. Hypotonic solutions are associated with an increased risk of developing hyponatraemia [2].

Once fluid volume has been restored, glucose should be added to the saline solution in the maintenance phase of IV rehydration (0.9% NaCl with 5% dextrose).

Volume and rate of fluid replacement

  • Oral rehydration: Aim for 10-20ml/kg of ORS in frequent small amounts [15]. Replace deficit over 4 hours.
  • NG rehydration:
    • Two regimes have been described
      • Rapid NG replacement: 25ml/kg/hr of ORS over 4 hours [15]
      • Standard NG replacement: replace the deficit over the first 6 hours, then give maintenance fluids over next 18 hours. This slower regime is preferred in infants <6 months, in the presence of significant comorbidities, or for children with significant abdominal pain.
    • IV rehydration:
      • Resuscitation phase: If the child is clinically shocked, 20ml/kg boluses of 0.9% NaCl should be given. If shock persists after a second, and certainly after a third bolus, consider contacting the paediatric ICU team.
      • Standard IV rehydration regime
        • Calculate child’s total deficit and maintenance requirement and replace over 24hrs
      • Rapid IV rehydration regime
        • Rapid IV rehydration with 20ml/kg/hr of 0.9% saline for 2 to 4 hours, followed by oral rehydration is now recommended [2]. The WHO recommends that IV rehydration should be completed within 3 to 6 hours depending on age [1].
      • These regimes do NOT apply to children requiring fluids for another clinical reason (e.g. pneumonia)

Calculating deficit and maintenance

  • Replacing child’s deficit
    • Estimate if the child has a 5% or 10% deficit (see “assessment of dehydration” section above)
    • Estimated deficit (in ml) is 5% (or 10%) X child’s weight in kg X 10
  • Replacing child’s daily maintenance requirements (Holliday – Segar method) [2]
    • 100ml/kg for first 10kg of body weight, then
    • 50ml/kg for next 10kg of body weight, then
    • 20ml/kg for each subsequent kg of body weight
    • Divide this total by 24 to get the hourly maintenance fluid requirements
  • Total fluid replacement rate
    • Decide over how many hours you want to replace the estimated deficit and add the calculated hourly maintenance requirement

Clinical Shock

Resuscitation phase

  • Ensure patient airway, give high flow oxygen
  • Obtain urgent IV access
    • Measure baseline U&Es, blood glucose and venous blood gas
  • Give a fluid bolus of 20 ml/kg 0.9% saline
  • If remains shocked after first bolus
    • Give a second bolus
    • Consider other causes for shock
  • If remains shocked after second bolus
    • Give a further bolus
    • Consider discussion with paediatric intensive care team

Maintenance phase

  • Once symptoms and signs of shock have resolved
  • Calculate daily maintenance requirement
  • Use 10% estimate for deficit calculation
  • Consider adding potassium to fluids once serum level is known
  • Monitor clinical and laboratory response to fluid therapy, adjust subsequent fluids as appropriate
  • Discuss with paediatric team

Worked example

A 24 kg child responded to a 20 ml/kg fluid bolus and is no longer shocked. What is his initial hourly IV fluid requirement using the standard regime? What type of fluid would you prescribe?


Estimated deficit 10% for this category

Deficit = 10 X 24kg X 10 = 2400 ml

Daily maintenance = (100 ml/kg x 10 kg) + (50 ml/kg x 10 kg) + (20 ml/kg x 4 kg) = 1580 ml

Hourly requirement = (2400 + 1580) / 24 = 165 ml/hour if replacing over 24hrs

Consider adding potassium once serum levels are known.

Clinical Dehydration

Initial management

Initial management is oral rehydration

Continue to breastfeed (if applicable)

Otherwise use low osmolality ORS:

  • Calculate deficit (estimated at 5% in this category of child)
  • Calculate maintenance fluid requirements
  • Replace over 4 hours in frequent but small amounts (total replacement rate is usually 10-20ml/kg/hr)
  • Monitor response to oral fluids

Worked example

What is the hourly ORS requirement for a 24 kg child who is clinically dehydrated?


Estimated deficit 5% for this category; fluids will be replaced over 4 hours

Deficit = 5 X 24kg X 10 = 1200 ml

Daily maintenance = (100 ml/kg x 10 kg) + (50 ml/kg x 10 kg) + (20 ml/kg x 4 kg) = 1580 ml in 24 hrs

4 hour maintenance = (1580 ÷ 24) X 4 = 263ml

Hourly requirement for 4 hours of rehydration = (1200 + 263) ÷ 4 = 365 ml/hour

Child refuses to take ORS / continues vomiting

If ORS is refused by the child and there are no ‘red flags’, consider other fluids (i.e. milk, water)

Avoid fruit juices and carbonated drinks

Consider NGT placement if the child is unable to drink and/or vomits persistently

IV rehydration and/or admission may be required if symptoms do not settle

Discharge criteria

If oral fluid is tolerated over first hour, consider child for discharge home

Reassure parents or carers that oral rehydration is usually possible

Provide verbal advice to:

  • Complete the remainder of the 4 hour fluid challenge at home
  • Administer the fluid in small, frequent amounts
  • Breast feeding should be continued throughout rehydration
  • An age-appropriate diet should be started during or after initial rehydration (4-6 hours); dilution of formula is usually unnecessary
  • Seek advice if the child refuses to drink or vomits persistently


No Clinical Dehydration

The aim is to prevent dehydration.[1]

Discharge home from the ED. 

Reassure parents and carers that most cases can be safely managed at home

Provide verbal advice to

  • Continue breast feeds and other milk feeds
  • Encourage fluid intake
  • Discourage fruit juices and carbonated drinks
  • If increased risk of dehydration, offer low osmolality ORS (i.e. Dioralyte®, Electrolade®) as a supplemental fluid
  • Seek advice from a healthcare professional if symptoms of dehydration develop
    • Appearing to get more unwell
    • Changing responsiveness (e.g. irritability or lethargy)
    • Decreased urine output
    • Pale or mottled skin
    • Cold extremities
  • Advise on the typical duration of symptoms and to seek advice if they do not resolve within these timeframes
    • Vomiting: 1-2 days, most stop within 3 days

Diarrhoea: 5-7 days, most stop within 2 weeks


Additional Therapies

The following therapies have been suggested in the management of paediatric gastroenteritis:


The majority of cases of paediatric gastroenteritis are viral and antibiotics are not required. Even cases of bacterial or protozoal infection are generally self-limiting [1].

Antibiotics should not be used for otherwise healthy children with Salmonella gastroenteritis as a carrier state may result [2].

Advice should be sought in cases of children with Escherichia coli O157:H7 infection regarding monitoring for haemolytic uraemic syndrome [1].

Antibiotics should only be given in cases of:

  • Suspected or confirmed septicaemia
  • Extra-intestinal spread of bacterial infection
  • Confirmed shigellosis, Vibrio Cholera, dysenteric Campylobacter or moderate-severe Clostridium difficile
  • Salmonella infection in infants or immunocompromised children only
  • Specialist advice should be sought in children who have recently returned from abroad

Anti-diarrheal agents

These are not recommended [1].


These are not recommended by NICE [1]. Subsequent reviews have suggested a potential role [16], with studies ongoing in this area.


These are not explicitly recommended by NICE [1].

Subsequent evidence showed that a single oral dose of ondansetron helps to stop vomiting and reduce the number needing IV fluid and admission [17]. Its use is recommended by American guidelines [18].

Ondansetron is associated with increased frequency of diarrhoea, so is not recommended in children with moderate to severe diarrhoeal symptoms. There is also a risk of prolongation of the QT interval, especially in children with electrolyte abnormalities, so ECG monitoring is recommended [2].

Hypernatraemic Dehydration

Resuscitate with the usual boluses of 20ml/kg 0.9% NaCl if child is shocked.

Thereafter, rapid correction can be dangerous – ideally oral rehydration should be used

Obtain baseline U&Es and blood glucose

If IV fluids are required:

  • Obtain urgent expert advice on fluid management
  • Commence isotonic fluids for deficit correction and maintenance (0.9% saline and 5% glucose)
  • Rehydrate slowly (normally over 48 hours)
  • Monitor serum sodium level frequently
    • Aim for a reduction of less than 0.5 mmol Na+/L per hour
  • Gradually attempt to introduce oral fluids early
  • If tolerated, complete rehydration with oral fluid therapy


Fluid and electrolyte imbalance

The risk of fluid and electrolyte imbalance is minimised by the use of oral hydration if possible. If IV rehydration is required the use of isotonic fluids, careful monitoring and adjustment of infusions is required.

Hypernatraemic dehydration

Hypernatraemic dehydration should be considered in those with suggestive clinical features. Baseline U&Es should be performed if there is concern. The risk of cerebral oedema can be minimised by slow rehydration (ideally with oral fluids) and careful monitoring of serum sodium levels.

Public health considerations

Parents and carers should be advised how to prevent spread of the infection:

  • Washing hands in warm, soapy water after going to the toilet, changing nappies and preparing, serving or eating food
  • Towels used by the infected child should not be shared
  • The child should not return to school (or childcare facility) until asymptomatic for 48 hours
  • The child should not swim in a public pool until asymptomatic for 2 weeks
  • Notify and act on the advice of the public health authorities if you suspect an outbreak of gastroenteritis


As with all critically ill patients, ensure notes are:

  • Timed (24 hour clock) and dated
  • Legible, accurate, sufficiently detailed and contemporaneous as possible
  • Signed with name, designation and GMC number against their signature

Complete with regards to discussions with senior colleagues and that the advice given is clearly documented.

  1. National Institute for Health and Clinical Excellence, Diarrhoea and vomiting caused by gastroenteritis in under 5s: diagnosis and management. Clinical guideline [CG84]. 2009.
  2. Guarino, A., et al.European Society for Pediatric Gastroenterology, Hepatology, and Nutrition/European Society for Pediatric Infectious Diseases evidence-based guidelines for the management of acute gastroenteritis in children in Europe: update 2014. J Pediatr Gastroenterol Nutr, 2014. 59(1): p. 132-52.
  3. Van Damme, P., et al., Multicenter prospective study of the burden of rotavirus acute gastroenteritis in Europe, 2004-2005: the REVEAL study. J Infect Dis, 2007. 195 Suppl 1: p. S4-S16.
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  10. Fuchs SC, Victora CG, Martines J. Case-control study of risk of dehydrating diarrhoea in infants in vulnerable period after full weaning. BMJ. 1996;313(7054):391-394. doi:10.1136/bmj.313.7054.391
  11. Victora, CG, et al., Breast-feeding, nutritional status, and other prognostic factors for dehydration among young children with diarrhoea in Brazil. Bull World Health Organ, 1992. 70(4): p. 467-75.
  12. Steiner MJ, DeWalt DA, Byerley JS. Is this child dehydrated? JAMA. 2004 Jun 9;291(22):2746-54.
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  14. Freedman, SB, et al., Gastroenteritis Therapies in Developed Countries: Systematic Review and Meta-Analysis. PLoS One, 2015. 10(6): p. e0128754.
  15. Royal Children’s Hospital Melbourne. Clinical Practice Guidelines: Gastroenteritis. 2015 November 2017];
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  17. Fedorowicz Z, Jagannath VA, Carter B. Antiemetics for reducing vomiting related to acute gastroenteritis in children and adolescents. Cochrane Database Syst Rev. 2011 Sep 7;2011(9):CD005506.
  18. Shane AL, Mody RK, et al.2017 Infectious Diseases Society of America Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea. Clin Infect Dis. 2017 Nov 29;65(12):e45-e80.