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Child Health Guideline Identifier


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For most children with gastroenteritis, there are three basic principles:

  1. Manage shock aggressively
    1. Isotonic fluids (normal saline or albumin)
    2. Intravenous or intra-osseous
    3. Boluses of multiples of 20 ml/kg
  2. If not in shock, rehydrate orally or nasogastrically
    1. Rehydration (2-4 hrs): Pedialyte 5 ml/min (25ml/5 min)
    2. Maintenance phase: 10 ml/kg per diarrhoeal stool
    3. Review the child frequently, support and educate the family
    4. There are some circumstances where IV fluids are indicated - see Intravenous Rehydration below
  3. Begin feeding early

Flow Chart for the Management of Suspected Gastroenteritis


* Details about IV rehydration and oral rehydration therapy below.


Is the Child Shocked?

  • See the Guideline on Shock
  • The child who is shocked may be limp, drowsy or comatose, with a rapid thready pulse, cold blue peripheries, hypotension and anuria. Less reliable signs include skin retraction and capillary refill.
  • Shock is an emergency. Establish IV or intra-osseous access. Take bloods (FBC, U&E, creatinine, calcium, glucose, blood cultures, venous gas). Give a bolus of 20 ml per kg of 0.9% sodium chloride or 5% albumin, and repeat as needed.
  • If the child does not respond well, treat as septicaemia, insert a urinary catheter and contact PICU. Notify your consultant. Lumbar puncture may be dangerous and should be deferred.
  • If there is a good response to bolus therapy, change to 0.9% sodium chloride and 5% glucose at maintenance rates while awaiting blood results.

Is This Gastroenteritis?

  • Acute gastroenteritis may be defined as diarrhoea of rapid onset, with or without vomiting, fever or abdominal pain. There is often a history of contact with another person with the same symptoms.
  • In a child with a diagnosis of gastroenteritis who has abdominal pain that continues for more than 24 hours, alternative diagnoses need to be considered and investigated for, consultant review needs to occur, and further surgical intervention may be required.
  • Not all vomiting is gastroenteritis. Bile stained vomiting means bowel obstruction until proven otherwise. Surgical conditions that may present with vomiting include pyloric stenosis (typical age about 6 weeks), intussusception (typical age about 6 - 10 months), appendicitis or intestinal malrotation.
  • Vomiting may precede diarrhoea in gastroenteritis, but you should suspect that isolated vomiting may be due to another cause. In every child with bile-stained vomiting, obtain a plain (erect/supine) abdominal X ray and a surgical opinion.
  • Other possible causes include:
    · appendicitis, pelvic abscess and other surgical abdominal conditions
    · acute metabolic / endocrine disease
    · bacterial gastroenteritis
    · diabetes
    · food poisoning (e.g. a Salmonella endotoxin or Staphylococcal exotoxin)
    · head injury or other trauma
    · other intracranial causes
    · poisoning
    · sepsis (especially urinary tract infection)
  • Management of gastroenteritis in very young infants and children with other complex medical conditions should be discussed with a senior.

Is the child dehydrated?

  • The best way to find out is to measure weight loss, but a recent weight is seldom available. Clinical estimate of the degree of dehydration is unreliable. Doctors usually overestimate the deficit, and may underestimate it if there is hypernatraemia.
  • In the management of dehydration, it is much more important to follow a child closely over time, than it is to calculate and replace a hypothetical figure for % dehydration.
Severity Symptoms  Physical signs 
Mild  thirsty, restless  None 
Slightly dry buccal mucosa 
Moderate lethargic, irritable  Dry buccal mucosa, absent tears 
Sunken eyes & fontanelle
Decreased urine output
Altered skin elasticity
Signs of ketosis (rapid shallow breathing, smell of ketones) 
Severe  limp, drowsy  Drowsiness
Shock (tachycardia, poor volume peripheral pulses, cool peripheries)
Hypotension is late/ominous sign
Skin retraction time > 2 seconds
Capillary refill time > 3 seconds 
As a rough guide, the child who is mildly dehydrated (≈5%) may be considered to have a 50 ml/kg deficit, and the child who is shocked (≈10 - 15%) may be considered to have at least a 100 ml/kg deficit.  

Do You Suspect Hypernatraemia or Hyperosmolality?

  • Hypernatraemia is almost entirely a complication of gastroenteritis in infants under the age of 12 months, particularly in those who have been given inappropriately concentrated formula or home-made rehydration solutions.
  • Hypernatraemia is uncommon in the population who present to Starship CED. Suspect and check for hypernatraemia in a moderately dehydrated infant whose history or physical findings (irritability and lethargy, fever, doughy feel to the skin) seem unusual for straightforward gastroenteritis.
  • See below for the management of hypernatraemia or hyperosmolality. NB: a child with a high urea or glucose may be hyper-osmolar in the presence of a normal serum [Na+].

Oral Rehydration Therapy (ORT)

This is the treatment of choice for dehydration from gastroenteritis. It is safer and more effective than IV therapy for all degrees of dehydration except shock.

ORT uses Oral Rehydration Solution, which takes advantage of glucose / sodium co-transport mechanisms in the small bowel.

[Electrolyte] (mmol/l)
Preparation  Na+  K+  Chloride  Citrate  Glucose (%) 
Pedialyte  45  20  35  30  2.5 

Certain principles must be remembered:

  • ORT is intensive. It depends on a lot of input from the child's caregiver, or the use of a nasogastric tube.
  • Pedialyte is the ORS of choice
  • The treatment of gastroenteritis with ORS occurs in two phases: rehydration and maintenance. Except in hypernatraemia, ORT aims for full rehydration within 4 hours.
  • The schedule suggested here for the rehydration phase is a standard rate of replacement for all dehydrated children who are not shocked, over 4 hours. The final volume given is determined by clinical assessment of when the child is rehydrated.
  • During the rehydration phase, fluid is given at a rate of 5 ml per minute, by teaspoon or syringe. The small volumes decrease the risk of vomiting. The rate (1 teaspoon / minute) is easy to calculate and administer for a parent sitting at the bedside. 25 ml every 5 minutes can also be used. If oral rehydration not successful, then naso-gastric rehydration should be used.
  • This rate of replacement is already maximal, and is not supplemented for ongoing losses. If the child's ongoing losses exceed an intake at this rate, the child will require nasogastric or intravenous fluids. This rate will rehydrate a moderately dehydrated 1 year old in 2 to 4 hours and a 2 year old in 3 to 5 hours (estimating diarrhoea at 0 -10 ml per kg per hour).
  • An alternative rate is 25 ml / kg /hr, over 4 hours, in small aliquots frequently
  • There must be frequent review (at least 2 hourly) in the rehydration phase.
  • Vomiting is not a contra-indication. Most children with gastroenteritis who vomit, will still absorb a significant percentage of any fluid given by mouth or NG.
  • Half strength apple juice has been shown to be a suitable alternative for children with mild gastroenteritis and minimal dehydration.


  • A single-dose of oral ondansetron may be effective at reducing hospital admission and the need for IV rehydration
  • Could be tried in children over 6 months of age if oral fluid challenge unsuccessful
  • Repeated doses have potential to increase diarrhoea 
  • Potential risk of arrhythmia when given IV (potential to prolong QT interval)
  • Ondansetron is contraindicated in children with prolonged QT interval
  • Not recommended for children < 6 months old or < 8kg
  • Should only be administered once in this setting.
Table 1: Ondansetron wafer dose (drug dose)
Weight Ondansetron wafer dose
8 -15 kg 2mg
15-30 kg 4mg
> 30 kg 8 mg

Anti-diarrhoeals are not recommended.

Nasogastric Tube

Delivery of ORS by constant infusion through a NG tube is very effective. If the clear diagnosis is gastroenteritis, choose NG infusion in preference to IV fluids in the child who is refusing ORS, has intractable vomiting or profuse diarrhoea, where there is no caregiver able to give ORS by mouth, or where trial of ORS by mouth has been unsuccessful. The principles are the same: to rehydrate fully within 4 hours in the iso-osmolar child, and more slowly in the moderately hypernatraemic child.

  • Rate for constant infusion is 25 ml/kg/hr Pedialyte to rehydrate over 4 hours.
  • Reduce rate to 15 ml/kg/hr in moderate hypernatraemia.
  • Medical review at least every 2 hours is mandatory during rehydration.

When the child is rehydrated, reduce the rate to a maintenance rate. If there is doubt about the child's ability to drink to keep up with ongoing losses, then the NG tube can be left in until this is clarified.

Intravenous Rehydration in Osmolar or Hypo-Osmolar Dehydration

Most children with gastroenteritis do not need IV therapy. Indications for an IV are:

  • Shock
  • If oral fluids might be unsafe (decreased consciousness, ileus, surgical abdomen)
  • Severe hyperosmolality (Na+ > 170, osmolality > 350)
  • The failure of oral or NG rehydration due to intractable vomiting (rare)
  • Children >4 years of age where ORS has failed (NGT may not be tolerated by older children)

After correcting shock, the speed of IV rehydration varies with osmolality. Change to oral or NG fluids if:

  • osmolality is < 350
  • the child has been fully resuscitated
  • the child is fully conscious and able to drink
  • there is no evidence of paralytic ileus change

Calculation of Osmolality
The serum osmolality can be measured directly, but is easy to calculate:
Serum osmolality (mOsm/l) = (2x Na+) + (2x K+) + Urea + Glucose

Definition  Serum Osmolality Serum Na+
Hypo-osmolar  < 280  < 130 
Iso-osmolar  280 - 319  130 - 150 
Hyperosmolar (Moderate)  320 - 350  > 150 
Hyperosmolar (Severe)  > 350  > 170 

Calculation of Maintenance Fluids (requirement per 24 hours)*

Age < 1 month 120 ml/kg/day 
Age > 1 month  as below 
Weight  Hourly maintenance fluid requirements
< 10 kg   4 ml/kg/hr 
10 - 20 kg   40 ml/hr + 2 ml/hr for every kg over 10 
> 20 kg  60 ml/hr + 1 ml/hr for every kg over 20.
Maximum IV maintenance fluid rate = 100ml/hr 

*Full maintenance fluids at 100% recommended for this condition.

Iso-osmolar Dehydration (Na+ 130 - 150 mmol/l, osmolality 280 - 319)

Use 0.9% sodium chloride and 5% glucose (or 0.9% sodium chloride and 10% glucose for neonates). Replace the rest of the deficit + maintenance over 24 hours. Give 1/2 the deficit in the first 8 hours, and the other 1/2 over 16 hours.


Hypo-osmolar Dehydration (Na+ < 130 mmol/l , Osmolality < 280)

Replace the water deficit as for iso-osmolar dehydration. If Na+ is < 120, admit to PICU. A slow infusion of 3% NaCl at 1.2 ml/kg/hr (0.6 mmol/kg/hr) will raise Na+ by 1 mmol/hr. Once Na+ is ≥ 120, replace the remaining Na+ deficit over 24 hrs by adding extra Na+ to the IV fluids.

In a child with symptomatic hyponatraemia (seizures or reduced level of consciousness) 3% NaCl - 1ml/kg can be given over 5 minutes - then review. Correction that is too rapid can lead to cerebral demyelination.

Note: the total Na+ deficit (mmol) = [135 - serum Na+(mmol/l)] x 0.6 x weight (kg)

If the child passes urine, and is not hyperkalaemic, add 10 mmol KCl to 500 ml IV fluid. If there is acidosis or profuse diarrhoea, more KCl than this may be needed.
Note: correction of the acidosis may cause a rapid fall in the serum K+.

Ongoing Losses While on Intravenous Rehydration
Weigh stools and replace every 1 gm of stool with 1 ml of fluid. Alternatively, approximate ongoing losses by giving 10 ml/kg per loose stool, and 2 ml/kg per vomit. In the child with profuse losses, calculate the fluid balance hourly.

If the child cannot drink, measure ongoing losses hourly and replace ml for ml by IV infusion of 0.9% sodium chloride over the following hour. Or, estimate ongoing losses and add the estimate to the IV infusion rate. If you do this, review the child often and adjust the infusion rate as losses change. If the child can drink, estimate ongoing losses as above, and replace them orally in frequent small aliquots.

There is no substitute for frequent clinical re-assessment. Weigh the child daily, and if in doubt, 12 or even 8 hourly.

Management of Hypernatraemia or Hyperosmolality

This is defined as a serum Na > 150 mmol / l, or a serum osmolality > 320 mOsm / l. Note that a child with a high urea or glucose may be hyper-osmolar in the presence of a normal serum Na+.

In the hyper-osmolar child, rapid correction of osmolality may cause cerebral oedema, convulsions and permanent brain damage. Severe hyperosmolar dehydration should be managed very cautiously with IV rehydration. Moderate hyperosmolar dehydration can be managed with IV rehydration, or with cautious modified ORT(see below).

Intravenous Rehydration of Hyperosmolar Dehydration

Moderate hyperosmolar dehydration: Na+ > 150 osmolality ≥ 320

Severe hyperosmolar dehydration: Na+ > 170 osmolality ≥ 350

Admit children with severe hyperosmolar dehydration to PICU.

In order to reduce the risk of cerebral oedema and brain damage during intravenous rehydration in hyperosmolality, aim to lower the serum Na+ slowly at a rate of 10 - 15 mEq in 24 hours, and the osmolality by no more than 0.5 - 1 mmol/hr.

(See 'Intravenous Rehydration' above for how to calculate osmolality and maintenance fluid requirements).

In moderate hyperosmolar dehydration, after initial resuscitation, replace the remaining deficit plus maintenance slowly at a uniform rate over 48 hours, using 0.45% NaCl and 2.5% Glucose.

daily volume

In severe hyperosmolar dehydration, after initial resuscitation, aim to replace the remainder of the deficit and maintenance over a period of 72 - 96 hours.

Never give a total IV volume of more than 200 ml/kg/day - usually give 100 -150 ml/kg/day. Calculate the osmolality at least 4 hourly, and measure it at least 12 hourly. If it is falling too quickly, reduce the rate of infusion by 20% and reassess in 4 hours.

As per sections in 'Intravenous Rehydration' above.

Ongoing Losses While on Intravenous Re-hydration
As per sections in 'Intravenous Rehydration' above.

Changing From IV Re-hydration to Oral Re-hydration
When the osmolality has fallen below 350 and the serum Na+ has fallen below 170, change to ORT (provided the child has been fully resuscitated, is fully conscious and able to drink, and has no evidence of paralytic ileus or a surgical abdomen).

Aim to continue to rehydrate the child slowly, at a rate of 15 ml / kg / hour of pedialyte. DO not give plain water or juice until the serum Na+ is < 150. When the Na+ is <150 fluids can be liberalised - manage as iso-osmolar dehydration.

Oral Re-hydration In The Presence of Moderate Hypernatraemia
Moderately hypernatraemic children can be safely rehydrated orally, giving Pedialyte at a maximum rate of 15 ml/kg/hr, being cautious not to allow a rapid drop in osmolality or serum Na+.

The rate of rehydration is about half that used in iso-osmolar dehydration. It is based on the assumption that most hypernatraemic children are severely dehydrated (≈10% or more), and allows for ongoing losses. If ongoing losses exceed this rate of replacement, the child will need nasogastric or intravenous rehydration. Electrolytes must be checked 4 hourly, and the rate of replacement slowed if the serum Na+ is falling at a rate faster than 1 mmol/hour.

Oral Maintenance Therapy

During the intensive acute rehydration phase of ORT ongoing losses are included in the standard rate of fluid replacement. After the acute phase, give both maintenance fluids and extra Pedialyte to replace the fluid in every loose stool, or the child will slip back into dehydration.

In children who are very unwell or have profuse losses, measure and replace stool loss as for children on IV therapy. In rehydrated children whose losses are not unusually profuse, advise parents to give both maintenance fluids and roughly 10 ml/kg for a diarrhoeal stool. As with ORT itself, this volume should be given in small aliquots rather than as a single large bolus.

Children who are not dehydrated often refuse Pedialyte. The following table analyses some of the alternative fluids often given by parents.

Note that undiluted juice or fizzy drink contains 5 - 15% sugar, and must be diluted to bring the sugar content down to 2% or less. In most cases, this means a dilution of 1 part juice to 5 (or more) parts water to avoid the risk of osmotic diarrhoea. If the parents have the container of juice or fizzy drink with them, you may be able to work out the dilution needed from the information on the packet.

Fluid  Na+   K+  HCO3-  Glucose (g/l)   Osmolality 
Cola  0.1  13  50 - 150 including fructose  550 
Ginger ale   1  50 - 150 including fructose   540 
Apple juice  20  100 - 150  700 
Chicken broth  250  0 0   450 
Tea   0  0
Lucozade   13 0.5    185  695 

Note that many commercially available fruit juices are largely based on apple juice.


Children with diarrhoea who are fed throughout the illness lose less weight and recover more quickly. During the acute phase (2 - 4 hours) of oral rehydration, it is reasonable to give oral rehydration fluids only, unless the child indicates a strong desire for milk or food as well. After this brief period however, feeding should be re-introduced. In the hypernatraemic child, milk may need to be introduced gradually to avoid a sudden fall in serum Na+.

Breast-feeding should never be discontinued. Formula can be given at standard strength. Children on fortified formulas need to have their fortification ceased during acute illness.

Solids can be given if the child is interested in them.

Lactose Malabsorption

This is not common. It is a clinical diagnosis based on symptoms of carbohydrate malabsorption (profuse stooling on lactose challenge and re-challenge), together with a positive stool fluid Clinitest for reducing substances. Anything more than a trace is positive (i.e. + ½% or more). A positive test is clinically irrelevant if not accompanied by diarrhoea. The test is meaningless in breastfed babies.

If lactose intolerance is confirmed, a lactose-free formula will need to be used until the intestine has recovered. This is usually no more than 4 - 8 weeks.


  • There is not yet sufficient data to recommend in Emergency Department
  • Probiotics should be avoided in children who are immunosuppressed or have an in-dwelling central venous catheter
  • Some strains reduce duration of diarrhoea - Lactobacillus GG and Saccaromyces boulardii
  • Proposed mechanisms:
    • Interact with intestinal microflora
    • Reduce intestinal permeability
    • Enhance phagocyte and NK cell activity
    • Increase faecal, salivary and systemic IgA

Is there bloody diarrhoea?

If there is blood or mucous in the stools, abdominal pain or systemic toxicity consider the diagnosis of bacillary dysentery. Treat with empiric antibiotics only if the child is immunocompromised or systemically unwell. If the child does not meet these criteria, you can afford to wait until culture results and specific sensitivities are available. In this situation, antibiotic therapy is almost never indicated.

Organism  Possible complications Antibiotic therapy 
Campylobacter  Neonatal septicaemia, convulsions, Guillain-Barre syndrome, Reiter's syndrome. May mimic appendicitis   In uncomplicated gastroenteritis, some benefit of therapy if given early. Usually the diagnosis is made too late for useful therapy (Erythromycin PO for 5 - 7 days)
Bacteremia is rare. Discuss with senior
Entero-invasive Escherichia coli    Generally not required
Enterohaemorrhagic E. Coli (usually 0157:H7) Haemolytic uraemic syndrome Antibiotics contraindicated
Bacteraemia, meningitis, osteomyelitis, typhoid fever  Age > 3 months:
Contra-indicated in uncomplicated gastroenteritis (may prolong duration of excretion of organism).
Age < 3 months:
7 days oral amoxicillin or Cotrimoxazole.

In bacteraemic/febrile/unwell infants < 3 months (CSF required), or children with complications, IV Ceftriaxone or Cefotaxime for 10-14 days or 4-6 weeks for meningitis or focal sepsis.
Shigella  Bacteraemia, colonic perforation, convulsions, haemolytic-uraemic syndrome, Reiter's syndrome, fulminant toxic encephalopathy  If bacteraemic, infants < 3 months, or children with complications, IV Ceftriaxone (discuss with senior)
In some cases treatment may be required for mild disease for reasons of public health. In this case, choose antibiotic by sensitivities 
Yersinia  Bacteraemia, conjunctivitis, glomerulonephritis, hepatic or splenic abscess, meningitis, osteomyelitis, pharyngitis, pneumonia, reactive arthritis, pseudoappendicitis  No evidence for antibacterial use in otherwise healthy non-neonates with enterocolitis.
In a sick, immunocompromised or neonatal case, discuss with senior. IV 3rd generation cephalosporin may be appropriate.

Information for families


  • Freedman SB, Pasichnyk D, Black KJL, Fitzpatrick E, Gouin S, Milne A, et al. (2015) Gastroenteritis Therapies in Developed Countries: Systematic Review and Meta-Analysis. PLoS ONE 10(6): e0128754. doi:10.1371/journal.pone.0128754
  • Reference JPCH 2017 S.Wen (under review) Non-typhoidal Salmonella infections in children: review of literature and recommendations for management. Whyte LA, Al-Araji RA, McLoughlin LM
  • Guidelines for the management of acute gastroenteritis in children in Europe. Archives of Disease in Childhood - Education and Practice Published Online First: 04 May 2015. doi: 10.1136/archdischild-2014-307253
  • 2015 Red Book Report of the Committee on Infectious Diseases AAP 30th Edition

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Document Control

  • Date last published: 05 April 2017
  • Document type: Clinical Guideline
  • Services responsible: General Paediatrics
  • Author(s): Raewyn Gavin, Elizabeth Wilson, Sarah Jamison
  • Owner: Raewyn Gavin
  • Editor: Greg Williams
  • Review frequency: 2 years

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