See also

Dehydration
IV fluids
Nasogastric fluids
Vomiting
Fluids calculator

Key points

1. In a child with red flag features or a child with vomiting without diarrhoea, consider alternative diagnoses (see Vomiting)
2. Most children do not require investigations, including stool testing
3. Whenever possible, the enteral route (oral or nasogastric) should be used for rehydration

Background

• Gastroenteritis is a common childhood illness that causes vomiting, diarrhoea and fever, often in sporadic seasonal outbreaks
• The cause may be viral or bacterial, but knowing the cause rarely changes management
• It is important to assess the degree of dehydration, as this influences route and rate of rehydration

Assessment

Any child with a red flag feature should prompt careful consideration of alternative diagnoses or risk of complications/severe disease (see Vomiting)

• Age under 6 months
• Bilious vomiting
• Haematemesis
• Diarrhoea for >10 days
• Severe abdominal pain
• Refusal to walk
• Past gastrointestinal/surgical history eg short gut, Hirschsprung, ileostomy
• Complex medical history eg renal, cardiac disease
• Post organ transplant
• Immunocompromised
• Representation/failure to respond to standard therapy

History

• Although vomiting may precede diarrhoea in the first 24-48 hours of gastroenteritis, in a vomiting child without diarrhoea, other causes must be considered
• Volume, frequency, duration of vomit and stool
• Blood or mucus in the stool: this suggests significant inflammation that may occur with bacterial infection or inflammatory bowel conditions
• Crampy abdominal pain
• Recent fluid intake: volume and type compared to usual (including hyper or hypotonic fluids)
• Urine output
• Infectious contacts
• Recent travel
• History of slow weight gain and/or fortification of feeds
• Recurrent presentations for similar symptoms

Examination

• Many children will have a normal examination, or generalised abdominal tenderness
• Pallor, irritability, altered conscious state, decreased activity level
• Signs of shock  
  • See Resuscitation: care of the seriously unwell child
• Focal abdominal tenderness
• Guarding
• Significant distension
• Absent or high-pitched bowel sounds 
• Degree of dehydration
  • Weight (bare in infants and where practical in young children)
    
  • See Dehydration

Management

Investigations

• For most children with presumed and uncomplicated gastroenteritis, no investigations are required

Blood glucose level (BGL), ketones and electrolyte measurement:

• All children requiring IV fluids should have serum electrolytes and glucose checked before commencing the infusion (typically when the IV is placed) and again within 24 hours if IV therapy is to continue
• May be required for children with
  • Severe dehydration, profuse or prolonged losses, or altered conscious state
  • Hypertonic fluid administration, eg sports drinks, Polyjoule, NG feeds
  • Prolonged hypotonic fluid administration, eg diluted formula or water-only rehydration. See hypernatremia and hyponatremia
  • Complex medical or surgical comorbidities or diuretic use
• Risk of accelerated starvation/ketosis. Ketotic hypoglycaemia can be a consequence of vomiting, more commonly in younger children

Stool culture or viral testing is not recommended, except in

• Unwell children or young infants with bloody diarrhoea
• Returned travellers with prolonged symptoms (>10 days)
• Immunocompromised patients with fever

Treatment

Many cases are self-limiting and only require encouragement of fluid intake and monitoring of hydration

Failure of initial management should prompt reconsideration of the diagnosis and management plan

Oral rehydration

Aim for 10 mL/kg/hr of oral rehydration solution (ORS) eg Gastrolyte^TM, Hydralyte^TM, Pedialyte^TM

• In mildly dehydrated children who are refusing ORS, short term flavoured ice block or diluted apple juice in 1:1 ratio with water can be offered
• Stop any feed fortification eg extra scoops of formula or Poly-Joule^TM
• If breastfed, continue breast feeding, but more often (or with additional ORS supplementation if appropriate) to maintain hydration

If oral rehydration fails with ongoing risk of dehydration, rapid or slow NG rehydration may be appropriate. Failure to tolerate NG should lead to IV rehydration if clinically dehydrated

IV rehydration may be preferred in older children if NG is not tolerated or is not appropriate

Refer to

• Dehydration 
• NG fluids 
• IV fluids 
• Vomiting 

Medications

Ondansetron can be administered to support hydration therapy in children and infants >6 months with persistent nausea or vomiting

Recommended initial ondansetron doses (oral)

• Ongoing ondansetron dosing is 0.15 mg/kg
• Other anti-emetics are not routinely recommended due to side effects
• Response to anti-emetics does not confirm diagnosis
• Anti-spasmodics and anti-diarrhoeal medications are not recommended
• There is currently insufficient evidence to support the use of probiotics to reduce the symptoms of acute gastroenteritis
• Antibiotics should be reserved for treatment of enteritis-associated sepsis or specific bacterial pathogens in selected cases (eg Salmonella Typhi, non-typhoidal salmonella in patients under 3 months, immunocompromised or with sepsis) or with severe Clostridioides difficile infection. See Antimicrobial guidelines

Consider discharge when

• Once rehydrated, a normal diet can be recommenced
• Temporary lactose restriction should not routinely be advised but if stool frequency increases, it may be considered
• Diarrhoea may persist

Consider consultation with local paediatric team when

• Initial rehydration unsuccessful and/or significant ongoing losses
• Complex comorbidities
• Electrolyte abnormalities
• Diagnosis is unclear
• Red flag features

Consider transfer when

• Severe electrolyte disturbance
• Shock requiring 40 mL/kg in fluid boluses

For emergency advice and paediatric or neonatal ICU transfers, see Retrieval services

Consider discharge when

Tolerating oral intake and nil/mild dehydration.

Parent information

Gastroenteritis factsheet (NSW)
Gastroenteritis in children (Qld)
Gastroenteritis Kid's Health Info (Vic) (pdf)
Gastroenteritis (WA)

Last updated August 2025