Cyclical vomiting


These guidelines have been produced to guide clinical decision making for the medical, nursing and allied health staff of Perth Children’s Hospital. They are not strict protocols, and they do not replace the judgement of a senior clinician. Clinical common-sense should be applied at all times. These clinical guidelines should never be relied on as a substitute for proper assessment with respect to the particular circumstances of each case and the needs of each patient. Clinicians should also consider the local skill level available and their local area policies before following any guideline. 

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To guide Emergency Department (ED) staff with the assessment and management of cyclical vomiting.


Cyclical vomiting syndrome is a recurrent episodic gastrointestinal disorder that can be identified by the occurrence of three or more episodes of intractable nausea and vomiting lasting from hours to days, separated by symptom free intervals lasting weeks to months.


  • In the majority of patients with cyclical vomiting syndrome (CVS) the onset is in the pre-school / early school age years (3-7 years).1
  • Many children grow out of cyclic vomiting syndrome by their pre-teen or early teenage years. However, some authors report that up to 75% of children with CVS will go on to develop migraine headaches by age 18 year (there is often a strong family history of migraine).1
  • Each patient's attacks tend to be stereotypical with regard to onset, periodicity, duration and intensity of symptoms.


  • Nausea and vomiting episodes as described.
  • The diagnosis of cyclical vomiting syndrome is generally not one for the ED, as differential diagnoses are broad, including endocrine, neurological and metabolic diseases.2
  • Generally, the patients will have previously been seen and assessed by a paediatric specialist and have been advised to present to the ED for treatment as soon as an episode of vomiting has started.


  • Exclude other causes of vomiting (consider neurological, surgical and infectious causes)
  • Assess hydration status
    • check blood glucose levels (BGL)
    • check electrolytes if clinically indicated
  • There are to date no controlled therapeutic trials on treatment of cyclical vomiting, and the treatment remains largely empirical.
  • In patients who experience a prodrome, use of oral anti-emetics, non-steroidal anti-inflammatories or sumatriptan may abort an episode before it becomes full-blown.
  • Patients who are prone to severe attacks which cannot be controlled at home should be admitted to hospital, and treatment with intravenous fluid should be started as soon as possible.
  • The treatment regimen that is instituted in individual patients is generally documented in their previous hospital records, and that treatment protocol should be followed.
  • Acute management is based on supportive and symptomatic care:
    • Administer IV hydration with sodium chloride 0.9% + glucose 5% fluid.
      • Consider bolus 10-20 mL/kg of sodium chloride 0.9% if dehydrated.
    • Anti-emetic medication.
Ondansetron is generally the first line anti-emetic (patient age > 2 years)
  •  0.15 mg/kg/dose IV (maximum 8 mg) every 8 hours.4
  • PO or sublingual may be used for patients with mild presentation.2
  • Doses of up to 0.3-0.4 mg/kg/dose every 4 to 6 hours [to a maximum of 8 mg/dose and 32 mg/day] have been used for cyclical vomiting.9 Such doses should only be given after consultation with a Consultant and a baseline echocardiogram (ECG) performed (risk of QT prolongation).
  • A proton pump inhibitor is useful for patients with epigastric pain and to prevent oesophagitis and haematemesis in Mallory Weiss tear.1,2 
  • Intermittent dosing
    • Children and adolescents:
      • < 40 kg: 1 mg/kg IV twice daily
      • ≥ 40 kg: 40 mg IV twice daily
  • Chlorpromazine may be useful in patients where ondansetron does not control nausea and vomiting.2 Dosing used is the same as for migraine as CVS is considered a migraine related disorder.

Chlorpromazine hydrochloride2
  • Use in children > 8 years old

    IV dose8:

    • 0.25 mg/kg (max 12.5 mg) in 10-20 mL/kg sodium chloride 0.9% (max 1 L) administered over 30-60 minutes.

    Ampoules contain 50 mg in 2 mL

    Chlorpromazine can prolong the QTc interval; this drug should be avoided in patients with cardiac disease, family history of sudden death, or potassium or magnesium deficiency (e.g., after persistent vomiting)

    Monitoring the patient receiving intravenous chlorpromazine hydrochloride:

    • Complete and record a full set of observations on the Observation and Response Tool and record additional information on the Clinical Comments chart.
    • Continue to monitor blood pressure, pulse and respirations every 15 minutes during the infusion and for 30 minutes after completion.
    • Continuous ECG and oxygen saturation monitoring.
    • Baseline neurological observations and continued hourly.
    • Chlorpromazine can cause dose-dependent sedation, postural hypotension and restlessness.
    • Keep patient recumbent for the duration of the infusion and for 30 minutes after completion of dose.


  • Patients may be discharged when euvolaemic and tolerating oral fluid.
  • Patients should be advised to avoid obvious triggers.2 


  1. Li BUK(2021) Cyclic Vomiting Syndrome. UpToDate. Accessed at
  2. Raucci, Umberto et al. “Cyclic Vomiting Syndrome in Children.” Frontiers in neurology vol. 11 583425. 2 Nov. 2020, Available from: doi:10.3389/fneur.2020.583425
  3. AMH Children’s Dosing Companion (2021) Australian Medicines Handbook Pty Ltd 2021, [Internet] Omeprazole; [Modified July 2021, Cited 4 Jan 2022] Available from:  Pantoprazole - AMH Children's Dosing Companion (
  4. AMH Children’s Dosing Companion (2021) Australian Medicines Handbook Pty Ltd 2021, [Internet] Ondansetron; [Modified July 2021, Cited 4 Jan 2022] Available from: Ondansetron - AMH Children's Dosing Companion (
  5. Gui, Shannon et al. “Acute Management of Pediatric Cyclic Vomiting Syndrome: A Systematic Review.” The Journal of pediatrics vol. 214 (2019): 158-164.e4. doi:10.1016/j.jpeds.2019.06.057
  6. Therapeutic Goods Administration, Product and Consumer Medicine Information: Largactil
  7. Villa X, Heyman, MB, Teach SJ. Approach to upper gastrointestinal bleeding in children. UpToDate. [Last Updated: 26 Jan 2023, Cited: 12 Dec 2023] Available from: Approach to upper gastrointestinal bleeding in children - UpToDate (
  8. Headache. Paediatric Improvement Collaborative Clinical Practice Guideline. [Last updated, December 2022, Cited: 12 December 2023] Available from: Clinical Practice Guidelines : Headache (
  9. Ondansetron: Paediatric Drug Information. UpToDate. [Cited: 12 December 2023] Available from: Ondansetron: Pediatric drug information - UpToDate (

Endorsed by: CAHS Drug & Therapeutics Committee  Date: Dec 2023

 Review date:  Dec 2026

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