Vomiting in children: the Australian general practice guide

Vomiting in a child is one of the most common reasons a parent calls a GP urgently. Most cases are viral gastroenteritis — self-limiting, manageable at home with oral rehydration. But a subset are surgical or metabolic emergencies that require same-day escalation. The clinical skill lies in telling them apart.

This article covers the age-banded approach to paediatric vomiting, the most important red flags, evidence-based treatment, and when to send a child to hospital. It is written to support conversations between parents and their GPs, not to replace clinical assessment.

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A. Core clinical framework

The first and most important question: is the vomit bilious?

Green or yellow (bilious) vomit in a child of any age is a surgical emergency until proven otherwise. Bilious vomiting indicates obstruction below the ampulla of Vater — the most dangerous cause is malrotation with midgut volvulus, which can cause bowel infarction and death within hours. Other surgical causes include jejunal atresia in neonates, intussusception in infants, and adhesive bowel obstruction.

Any child with bilious vomiting should go directly to the emergency department. Do not observe at home. Do not wait to see if it settles.

The second imperative: check the blood glucose

For any child who appears to have acute gastroenteritis, a fingerprick blood glucose is mandatory. Studies show that 30–40 per cent of children presenting with new-onset type 1 diabetes are initially diagnosed with gastroenteritis. Diabetic ketoacidosis (DKA) causes vomiting and abdominal pain that mimics gastroenteritis exactly. Missing DKA is dangerous: the child deteriorates rapidly, and delayed diagnosis is associated with cerebral oedema. A bedside glucose ≥ 11 mmol/L in a vomiting child who has not been given dextrose warrants urgent hospital transfer.

Age-banded differential diagnosis

The likely cause of vomiting differs markedly by age:

Neonates (0–28 days):

• Pyloric stenosis — projectile non-bilious vomiting, onset 2–8 weeks, hungry vomiter, metabolic alkalosis. Ultrasound confirms: pyloric muscle thickness ≥ 4 mm.
• Gastro-oesophageal reflux — common and usually physiological; bilious vomiting excludes this as the primary diagnosis.
• Overfeeding — soft regurgitation after feeds; baby thriving.
• Sepsis — fever, lethargy, poor feeding; vomiting one of many features. Requires urgent assessment.
• Surgical causes — bilious vomiting in a neonate is surgical until proven otherwise; includes duodenal atresia, malrotation.

Infants (1–12 months):

• Viral gastroenteritis — most common cause. Rotavirus, norovirus. Diarrhoea often accompanies vomiting.
• Intussusception — typically 6–24 months; episodic colicky abdominal pain, drawing up of legs, “red-currant jelly” stool (late sign). Air enema is diagnostic and therapeutic. Requires emergency surgical referral.
• Incarcerated inguinal hernia — irreducible lump in groin; requires emergency surgery.
• Urinary tract infection — vomiting and fever; urinalysis and urine culture.

Toddlers (1–5 years):

• Viral gastroenteritis — most common.
• Appendicitis — classical presentation is rare in young children; periumbilical pain migrating to right iliac fossa. Perforation risk is higher in young children because of diagnostic delay.
• Meningitis / encephalitis — fever, photophobia, neck stiffness, altered consciousness; non-blanching petechial rash in meningococcal disease. Any suspicion warrants emergency review.
• DKA (new or known type 1 diabetes) — check glucose.

School-age and adolescents (5–18 years):

• Viral gastroenteritis — common.
• Appendicitis — more classical presentation; peritonism.
• Cyclic vomiting syndrome (CVS) — stereotyped recurrent episodes, well between; migraine association.
• DKA — check glucose, especially first presentation.
• Cannabis hyperemesis syndrome — in teenagers with regular cannabis use; paradoxically relieved by hot showers; cessation of cannabis is the treatment.
• Functional nausea and vomiting — Rome IV criteria for functional dyspepsia, CVS.
• Pregnancy — in adolescent females; always consider and test where clinically appropriate.
• Raised intracranial pressure — vomiting (often without nausea) with headache, papilloedema, morning predominance; requires urgent neuroimaging.

Dehydration assessment

eTG Complete and RCH Melbourne recommend a clinical dehydration assessment:

• Mild (3–5%): alert, normal capillary refill (<2 sec), normal skin turgor, slightly dry mucous membranes. Manage at home with oral rehydration.
• Moderate (6–9%): irritable, capillary refill 2–4 sec, reduced skin turgor, dry mucous membranes, sunken eyes/fontanelle. Oral rehydration trial in practice; consider ED if not tolerating.
• Severe (≥10%): lethargic, capillary refill >4 sec, markedly reduced skin turgor, very dry mucous membranes, tachycardia, hypotension, mottled skin. Emergency transfer; IV or nasogastric rehydration needed.

History and examination

Key questions: duration and frequency of vomiting; colour (bilious?); recent food or medication history; contact with gastroenteritis; fever; blood in vomit; abdominal pain pattern; diarrhoea; urine output; weight loss; known diabetes or chronic conditions.

Examination: temperature; heart rate and BP; capillary refill; abdominal inspection (distension, visible peristalsis), palpation (tenderness, guarding, peritonism, mass), auscultation; check for hernias; assess fontanelle in infants.

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B. Evidence review

Ondansetron for acute gastroenteritis

Roslund et al. (2008) and the Cochrane meta-analysis on oral ondansetron both confirm that a single oral dose of ondansetron significantly reduces vomiting, decreases the need for IV fluids, and reduces hospitalisation rates in children aged six months and over with acute gastroenteritis. The number needed to treat is approximately 5 to prevent one child from needing IV therapy.

Dose: 0.15 mg/kg orally as a single dose; maximum 4 mg. Available as an orally dissolving tablet (Zofran Zydis 4 mg) — important for children who are vomiting continuously.

Important caveats:

• Not for bilious vomiting or any suspected surgical cause — antiemetics mask the clinical picture.
• Not recommended under six months (safety data limited).
• May increase stool frequency (loose stools are a recognised side effect).
• A prolonged QTc or concomitant medications that prolong the QT interval are relative cautions — check the medication history.

Oral rehydration solution

WHO-recommended low-osmolarity ORS (245 mOsm/L) is superior to standard high-osmolarity ORS for reducing stool output and vomiting in children with gastroenteritis. Commercial Australian products (Gastrolyte, Hydralyte) conform to this specification. Sports drinks, cordial, apple juice, and flat lemonade are inappropriate — their sugar concentration worsens osmotic diarrhoea and their electrolyte profile is incorrect.

Volumes: for mild dehydration, give 50 mL/kg of ORS over four hours; for moderate, 100 mL/kg over four hours. Breastfed infants should continue to breastfeed throughout.

What the evidence does not support

• Antiemetics (metoclopramide, promethazine) in children — these agents have significant extrapyramidal side effects in paediatric patients and are not recommended.
• Routine antibiotics for gastroenteritis — viral in most cases; antibiotics are reserved for specific bacterial causes (Salmonella in immunocompromised hosts, Campylobacter with severe systemic illness).
• BRAT diet (bananas, rice, applesauce, toast) — this unnecessarily restricts nutrition; regular age-appropriate feeds should recommence as soon as the child can tolerate them.

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C. Specific conditions

Pyloric stenosis

Projectile non-bilious vomiting in a 2–8-week-old baby who remains hungry after vomiting should prompt urgent evaluation for pyloric stenosis. The GP examination may identify the hypertrophied pylorus as an “olive” in the right upper quadrant. Biochemistry shows a hypochloraemic, hypokalaemic metabolic alkalosis. Abdominal ultrasound confirms the diagnosis (pyloric muscle thickness ≥ 4 mm, length ≥ 16 mm). The baby requires hospital admission for rehydration and electrolyte correction before pyloromyotomy. Urgent emergency department referral is appropriate.

Intussusception

The classic triad in an infant (6–24 months) is episodic severe colicky abdominal pain (drawing up legs, inconsolable crying), vomiting, and “red-currant jelly” stool. However, the classical triad is present in only a minority — vomiting and colicky pain alone should prompt consideration. Abdominal ultrasound confirms the intussusception. Air enema is diagnostic and therapeutic in around 90 per cent of cases. Surgical reduction is needed when air enema fails or peritonitis is present.

Cyclic vomiting syndrome

Rome IV criteria for cyclic vomiting syndrome: ≥2 episodes in the preceding six months of intense nausea and vomiting lasting ≥1 hour, returning to baseline health between episodes, with a stereotyped pattern for that individual. Strong association with migraine; management mirrors migraine therapy. Identify and avoid triggers. Abortive therapy: ondansetron at onset of prodrome; sumatriptan (intranasal or oral) for children aged 12 years and over. Preventive therapy for frequent severe episodes: propranolol, amitriptyline, or cyproheptadine.

Cannabis hyperemesis syndrome

In teenagers with regular cannabis use, cyclic vomiting with a hallmark feature of relief from prolonged hot showers or bathing should prompt consideration of cannabis hyperemesis syndrome. Topical capsaicin cream to the abdomen has some evidence as an acute measure. The definitive treatment is cannabis cessation. GP counselling using a brief intervention approach and referral to youth drug and alcohol services is appropriate.

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D. Australian general practice operations

MBS items

Paediatric vomiting is managed under standard GP attendance items. Key item numbers include:

• Items 23, 36, 44 — Level B, C, and D GP consultations for acute assessment.
• Item 10992 — point-of-care testing (e.g., blood glucose measurement in practice).
• Item 10981 / 73805 — urine MCS for urinary tract infection as a cause of vomiting.
• Item 65060 — biochemistry profile (electrolytes, glucose, bicarbonate for dehydration and metabolic alkalosis assessment).
• Item 55068 — abdominal ultrasound (pyloric stenosis, intussusception) — ordered by GP, performed by radiologist.
• Items 2715 / 2717 — Mental Health Treatment Plan if functional GI disorder or anxiety underpins recurrent vomiting.
• Item 715 — ATSI Health Assessment for Aboriginal and Torres Strait Islander children.

PBS prescribing

• Ondansetron 4 mg orally dissolving tablet (Zofran Zydis) — General Schedule; prescribe as a single or short course at 0.15 mg/kg dose. Available on PBS for nausea and vomiting in children.
• Oral rehydration salts (Gastrolyte) — not PBS-listed; available OTC; cost-effective.
• Metoclopramide — not recommended in children ≤ 20 years (extrapyramidal side effects); avoid prescribing in this age group.

Oral rehydration in practice

GPs can supervise a trial of oral rehydration in practice for a child with mild to moderate dehydration — this is a well-established approach recommended by RCH Melbourne. Give ondansetron if vomiting is a barrier to oral intake. Observe the child taking fluid in practice. If the child tolerates 100–200 mL over 30 minutes and does not deteriorate, discharge with a detailed safety-net plan is appropriate.

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E. Special populations

Aboriginal and Torres Strait Islander children

Gastroenteritis in Aboriginal and Torres Strait Islander children in remote and rural settings may be more severe due to baseline nutritional status, crowded living conditions, and recurrent infections. Dehydration risk is higher. The threshold for hospital referral should be lower. The MBS item 715 health assessment can be used to review nutrition, immunisations, and household water and sanitation factors in the context of recurrent gastroenteritis.

Immunocompromised children

Children receiving chemotherapy, those with primary immunodeficiency, or those on long-term immunosuppression may have atypical presentations of gastroenteritis. Bacterial infections (Salmonella, Campylobacter) are more severe and more likely to bacteraemia. Threshold for stool culture, blood culture, and antibiotic treatment is lower. Oncology team should be contacted for children under active cancer treatment.

Children with disabilities

Children with complex neurodisability may not be able to communicate pain, nausea, or abdominal discomfort. Vomiting in this group warrants a lower threshold for investigation for surgical causes, as presentation is often delayed and atypical.

Neonates under 4 weeks

Any vomiting in a neonate under four weeks warrants careful assessment. Bilious vomiting is a surgical emergency. Forceful non-bilious vomiting is pyloric stenosis until proven otherwise after the second week of life. Non-projectile vomiting after feeds in a well, thriving neonate is likely physiological reflux. Fever in a neonate of any kind requires urgent sepsis assessment.

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When to escalate

Send the child to the emergency department immediately if:

• Bilious (green or yellow) vomiting — surgical emergency.
• Blood glucose ≥ 11 mmol/L in a child with vomiting who has not received dextrose — possible DKA.
• Signs of severe dehydration: lethargic, tachycardic, prolonged capillary refill, mottled skin.
• Suspected appendicitis or peritonism: localised guarding, rebound tenderness, rigidity.
• Non-blanching petechial or purpuric rash with fever — possible meningococcal disease; call 000.
• Persistent vomiting in a neonate under 4 weeks with projectile pattern — pyloric stenosis needs urgent evaluation.
• Vomiting with headache and papilloedema or altered consciousness — raised intracranial pressure.
• The parent has a strong gut feeling something is seriously wrong — this is clinically valid and warrants re-examination or ED review.

Consider same-day GP review or telephone follow-up within 12–24 hours for:

• Moderate dehydration managed at home — reassess tolerance.
• Any child not improving or worsening on conservative measures after 24 hours.
• A parent who does not feel confident managing at home.

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What this article is and is not

This article provides general patient education about paediatric vomiting based on current Australian clinical guidelines. It is not a substitute for clinical assessment. The management of a vomiting child depends on their age, weight, degree of dehydration, and the clinical picture — all of which require a GP to assess in person.

Nothing in this article constitutes a recommendation to give any medication to a child without first consulting a GP or healthcare professional. If your child has green vomit, is very unwell, or you are worried, go to the emergency department or call 000.

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Sources cited

• Roslund G et al. — Paediatric ondansetron for acute gastroenteritis (Paediatrics 2008)
• RACGP — Acute gastroenteritis in children
• eTG complete — Gastroenteritis in children
• Royal Children’s Hospital Melbourne — Vomiting and gastroenteritis clinical guidelines
• Royal Children’s Hospital Melbourne — Pyloric stenosis
• NICE CKS — Gastroenteritis
• WHO — Oral rehydration salts: production of the new ORS
• Cochrane — Oral ondansetron for vomiting in acute gastroenteritis
• Rome IV criteria — Cyclic vomiting syndrome
• Paediatric & Adolescent Diabetes Australia — Type 1 diabetes DKA presentation
• HealthDirect Australia — Vomiting in children
• Raising Children Network — Vomiting