Cyclic Vomiting Syndrome: Causes and Treatment

Cyclic vomiting syndrome (CVS) is a disorder of the gut-brain axis characterized by recurring attacks of severe nausea and vomiting, stereotypical in onset and course, separated by periods of complete or near-complete recovery. In the same person, episodes often resemble each other: they begin at the same time of day, last for hours to days, and then remit for weeks or months. It is this recurrence and inter-episode well-being that distinguishes CVS from most organic causes of vomiting. [1]

SCR occurs at any age. In children, the prevalence is estimated at around 2% or higher; some patients outgrow it, but for many, the condition persists into adulthood, sometimes transforming into migraine. In adults, SCR was long underestimated; today, it is considered a common diagnosis in gastroenterology and neurology, particularly in people with a personal or family history of migraines. [2]

According to the Rome IV criteria, the diagnosis is made clinically: ≥2-3 typical attacks per year (in the pediatric version, more often ≥2 per 6 months), stereotypy, the absence of an organic disease explaining the symptoms, and interictal "lucid" intervals. These are the criteria for a disorder of the interaction of the gut and brain, and not a "stomach disease." [3]

Important: In Russian-language practice, CR is sometimes confused with "functional vomiting," gastroparesis, or gastroenteritis. The key clue is cyclicity and a return to normal between episodes. Any "red flags" (blood, weight loss, nocturnal symptoms with awakening pain, neurological deficits) are a reason to look beyond CR. [4]

Why does it happen (pathophysiology and associations)

There is no single cause: CR is considered a neural network disorder with overlap with the migraine continuum. In many patients (especially in childhood), attacks are triggered by the same triggers as migraines (sleep deprivation, hunger/carbohydrate overload, stress), and migraines run in the family. This supports the idea of a role for central pain/nausea mechanisms and neurotransmitters. [5]

SCI is often associated with autonomic dysfunction (orthostatic intolerance, POTS) and other disorders of the gut-brain axis. Clinical manifestations—pallor, myriasis, hypersalivation, chills—are explained by autonomic hyperreactivity. This also explains the benefit of certain strategies aimed at modulating the autonomic nervous system. [6]

The contribution of mitochondrial vulnerability is discussed. Small series have shown the benefit of coenzyme Q10 and L-carnitine in prevention, especially in combination with anti-migraine therapy; the evidence base is limited, but these supplements have been included in several consensus guidelines as conditionally recommended options in cases of intolerance/insufficient response to standard treatments. [7]

CRS must be distinguished from cannabinoid hyperemesis syndrome (CHS), a similar clinical condition associated with chronic cannabis use and characteristic relief from hot showers. In CHS, the key treatment is complete cannabis withdrawal; this association is not present in patients with CRS. Correct differentiation saves years of wasted therapy. [8]

What does a seizure look like and what triggers it?

A typical episode goes through four phases: prodrome (increasing nausea/faint autonomic symptoms), hyperemic phase (repeated vomiting/dry retching, sometimes every 5-10 minutes), recovery (drowsiness, exhaustion), and intermission (complete well-being). There are often "personal" triggers: lack of sleep, hunger/sugar snacks, stress/anxiety, strong odors, menstruation, long trips. [9]

In children, the precursor is often abdominal migraine or migraine headaches. In adults, an attack may "mask" as gastroenteritis, especially during initial presentations; the recurrence of the scenario and the absence of contact/infectious factors are concerning. [10]

During an attack, risks include dehydration, electrolyte imbalances (hypokalemia, metabolic alkalosis), esophagitis, mucosal ruptures (Mallory-Weiss), and dental enamel erosion. Frequent hospitalizations increase anxiety and avoidance behavior patterns, so a pre-planned management plan reduces both the duration and the "cost" of episodes. [11]

Between episodes, some patients experience mild nausea/motion sickness, but a diagnosis of CR requires normal days when a person eats, drinks, and leads a normal life. This is why prevention and addressing triggers are important, not just emergency treatment during crises. [12]

Diagnostics: What You Need (and What You Don't)

The basis is the clinical picture according to Rome IV and the exclusion of “red flags” (blood, weight loss, fever, neurological examination, persistent night pain, progressive deterioration, biochemical shifts). Typical initial tests: complete blood count/biochemistry, electrolytes, glucose, pregnancy test (in women), and, if indicated, TSH, cortisol, and ferritin. Instrumental studies are as clinically indicated; “screening” CT/endoscopy is not necessary for typical CR. [13]

Distinguishing from CNS. Any regular cannabis use requires active questioning. CNS is characterized by frequent use over many years, relief from hot water, and resolution of symptoms with persistent abstinence. If a person has not stopped using for at least 2-3 months, a diagnosis of CNS is questionable. [14]

Gastroenterological "mimicry." Rumination syndrome (tongue-dropping, "passive" passage of food), gastroparesis (slow emptying on a 4-hour scintigraphy), peptic ulcer disease, biliary colic. These diagnoses have their own objective signs and do not demonstrate a pure cyclical pattern with long-term remissions. [15]

In children with an atypical course or early onset (especially ≤2-3 years), metabolic screening (amino/organic acids, acylcarnitines) and neurological assessment are discussed; however, in most cases, clinical verification according to consensus pediatric guidelines is sufficient. [16]

How to stop an acute attack (at home and in hospital)

The first goal is to "break" the attack early, before it reaches full force. A home "rescue plan" typically includes ondansetron ODT (or another 5-HT3 antagonist), analgesia/sedation (oral or rectal diphenhydramine/promethazine at age-appropriate doses), a migraine-specific triptan (nasal/subcutaneous sumatriptan), and rest in a dark, quiet room. If this does not help within 1-2 hours, proceed to the emergency department plan. [17]

In hospital: IV rehydration with electrolyte correction (especially potassium), ondansetron/granisetron, in severe attacks - aprepitant as an antiemetic/abortive therapy; if indicated - sumatriptan (if there are no contraindications), antihistamines/phenothiazines under ECG monitoring. It is important to avoid opioids: they impair motility and can perpetuate hyperemesis. [18]

In children and adolescents with a pronounced migraine-related disorder, nasal/subcutaneous triptans are used abortively; aprepitant is increasingly used in resistant episodes and is included in protocols as a "second-line" option. It is useful for healthcare providers to have a standardized ED protocol—this reduces the time to relief and the length of hospitalization. [19]

After the attack has been stopped, a soft liquid diet, gradual expansion of the diet, pain control without opioids, discussion of prevention (below) and provision of a written plan for the next episode to act more quickly. [20]

Prevention: What is prescribed "between episodes"

First-line therapy in adults is amitriptyline (or another tricyclic) with slow titration to an effective dose; topiramate and aprepitant are recognized as alternatives/add-ons in cases of intolerance or inadequate response. These recommendations are the consensus of the ANMS/CVSA experts and are confirmed by the AGA updates. [21]

In children, initial prophylaxis depends on age: cyproheptadine (younger children), amitriptyline (schoolchildren/adolescents), propranolol – an option for the migraine phenotype; topiramate is considered in refractory cases. The updated NASPGHAN 2025 guidelines systematize dosages and algorithms for transitioning between classes. [22]

Mitochondrial cofactors (coenzyme Q10, L-carnitine ± riboflavin) may be considered as an adjunct to basic prophylaxis; some patients report a reduction in the frequency/severity of episodes. These are conditional recommendations with a moderate-to-low level of evidence—it is important to clarify expectations and monitor tolerability. [23]

Finally, trigger hygiene: regular sleep, eating without long "hunger windows" (especially in the morning), stress management, limiting simple sugars, and avoiding triggers (alcohol, excess caffeine, and glutamate in sensitive individuals). Patients with orthostatic symptoms may benefit from increased salt/fluid intake and low-intensity exercise. [24]

How does CSR differ from cannabinoid hyperemesis (CHS)?

In CHS, there is almost always a history of long-term, frequent cannabis use; compulsive hot showers/baths are characteristic as temporary relief. The primary treatment is complete cannabis withdrawal with gradual symptom resolution; without this, any antiemetics provide only a short-term effect. SCR does not have such a strong association with cannabis. [25]

Clinically, both conditions are cyclical, but with CHS, abdominal pain around the navel is more pronounced, and interictal intervals shorten as consumption progresses. If the patient has not stopped using for a significant period of time, it is too early to diagnose CHS. If in doubt, an honest conversation and observation during withdrawal are recommended. [26]

It's important to avoid stigmatization: people often use cannabis as a "self-medication" for nausea/pain, without associating it with flare-ups. A clear explanation of the mechanics and expected improvement after cessation increases adherence. [27]

In the emergency department, acute CHS sometimes responds to capsaicin ointment (distraction action via TRPV1) and haloperidol/droperidol; these are not standards for CRS and do not replace cannabis cessation.[28]

A plan for every day and for a rainy day

It is helpful to have an individualized plan: 1) early initiation of abortive medications (ondansetron ODT ± triptan), 2) a clear threshold for a trip to the hospital (inability to drink for ≥4-6 hours, signs of dehydration, vomiting bile/blood, severe weakness), 3) a list of medications that have/have not helped in the past, and 4) a reminder for the ED staff. Such a "patient passport" shortens the path to relief. [29]

During the interictal period, maintain a sleep schedule, eat breakfast within 30-60 minutes of waking, snack every 3-4 hours, limit long car rides/overheating, and implement a stress management plan (breathing exercises, cognitive techniques). Brief instructions are helpful for families and schools to prevent the "amplification" of anxiety and mistrust. [30]

Patients with severe vegetative concomitant symptoms (orthostasis, tachycardia) are helped by behavioral measures of hydration/salt, sometimes by a referral to a cardiologist/neurologist to clarify POTS and select therapy; stabilization of autonomic dysfunction often reduces the frequency of episodes of CR. [31]

Regular prophylaxis reviews (every 3-6 months), monitoring of side effects, and flexible switching of drug classes increase the chance of sustained remission and reduce the cost of treatment. This is especially important in adolescents and young adults. [32]