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 staff with the assessment and management of cyclical vomiting.


Cyclical vomiting syndrome is a functional 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).
  • 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 develop migraine headaches by age 18.
  • 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 not one for the emergency department
  • Generally the patients will have previously been seen and assessed by a paediatric specialist, and have been advised to present to the Emergency Department for treatment as soon as an episode of vomiting has started.


  • 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 or non-steroidal anti-inflammatories 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 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.
  • Generally a proton pump inhibitor needs to be given.
  • 2 mg/kg stat IV (max 80 mg), then
  • 1mg/kg/dose (max 40 mg) 8-12 hourly IV is suitable

With an anti-emetic medication:

Ondansetron is generally the first line anti-emetic (patient age > 2 years)
  • This can be given as either a 6-8 hourly bolus dose, or as a continuous infusion.
    • Intermittent dosing: Ondansetron 0.15 mg/kg/dose IV (infused over 15 minutes) every 6-8 hours
    • Continuous infusion: Ondansetron 0.4 mg/kg (max 8 mg) IV over 15 minutes, then 1 mg/hour for 12-24 hours. Note that this is a standard 1 mg per hour, irrespective of the child's weight. This may need to be continued depending on the clinical status of the patient.

In some patients a benzodiazepine such as lorazepam may be useful.

If intravenous lorazepam is available, it may be given in the following dose:
  • 25 - 100 micrograms/kg/dose 6-hourly (maximum 4 mg per dose)


  1. Desilets DJ (2014) Cyclical Vomiting Syndrome. UpToDate. Accessed at
  2. Paediatric Pharmacopoeia - 13 Edition 2002. The Royal Children's Hospital.

Endorsed by:  Executive Director, Medical Services  Date:  Oct 2021

 Review date:   Apr 2022

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