Definition and epidemiology
Cyclic vomiting syndrome (CVS) is a functional gastrointestinal disorder characterised by recurrent, stereotypical episodes of intense vomiting separated by symptom-free intervals of normal health. It is part of the spectrum of disorders linked to migraine, and most children have a personal or family history of migraine. Onset is typically between ages 3 and 7, though it occurs at any age. Prevalence is estimated around 0.2–1% of children. It is frequently misdiagnosed and under-recognised, leading to repeated emergency visits, unnecessary investigations and dehydration before the pattern is appreciated.
Clinical features
The hallmark is paroxysmal, stereotypical attacks: each episode resembles the last in onset time (often nocturnal or early morning), symptoms and duration. Vomiting is intense and high-frequency (“≥4 emeses per hour at peak” classically) and may be accompanied by retching, pallor, lethargy, abdominal pain, photophobia, headache and autonomic features. Episodes last hours to days, then resolve completely with return to baseline health for weeks to months. Identifiable triggers include infection, psychological stress (positive or negative excitement), menstruation, fasting, and certain foods. Between attacks the child is entirely well — a key discriminator from organic disease.
Diagnosis
CVS is a clinical, largely exclusion-based diagnosis. The Rome IV criteria require: the occurrence of ≥2 periods of intense, unremitting nausea and paroxysmal vomiting lasting hours to days within a 6-month period; episodes that are stereotypical in each patient; episodes separated by weeks to months with return to baseline health between them; and, after appropriate evaluation, symptoms not attributable to another condition. (NASPGHAN consensus historically required ≥5 attacks in total, or ≥3 in 6 months, reflecting an emphasis on diagnostic certainty over Rome IV’s earlier-diagnosis aim.) Targeted investigation excludes mimics — metabolic, neurological and surgical causes — guided by red flags rather than performed blanket.
See the full criteria: Cyclic Vomiting Syndrome
Red flags
These features argue against CVS and mandate investigation for an organic cause:
- Bilious vomiting, severe abdominal tenderness, or signs of bowel obstruction (consider malrotation with intermittent volvulus)
- Abnormal neurological examination, severe morning headache, or vomiting precipitated by intercurrent illness/fasting (consider raised intracranial pressure or a metabolic disorder)
- Progressive worsening, lack of well intervals, or a non-stereotypical pattern
- Hematemesis, severe electrolyte disturbance, or hepatomegaly
- Onset in infancy or with developmental regression
Management overview
Care has three arms. Abortive/acute: early triptan (e.g. sumatriptan), antiemetics (ondansetron), aggressive IV rehydration with dextrose-containing fluids, a quiet dark environment, and sedation (e.g. with an antihistamine or benzodiazepine) to terminate severe episodes. Prophylaxis for frequent or disabling attacks: cyproheptadine (first-line under ~5 years) or amitriptyline/propranolol (older children), with coenzyme Q10 and riboflavin as adjuncts. Lifestyle: trigger avoidance, regular meals and sleep, stress management, and reassurance. Provide a written action plan so families can intervene early at the prodrome. Prognosis is good; many children outgrow CVS, though some evolve to migraine headaches.
References
- Hyams JS, et al. Gastroenterology. 2016;150:1456–1468 (Rome IV).
- Li BUK, et al. J Pediatr Gastroenterol Nutr. 2008;47:379–393 (NASPGHAN consensus).
- Nelson Textbook of Pediatrics, 21st ed.
Decision support for qualified clinicians only — verify against current primary guidelines and your clinical judgement.