Cyclic vomiting syndrome

Symptoms and typical course

Most people with CVS experience a predictable sequence during an attack: a prodrome (mild nausea, pallor, or headache), a vomiting phase with frequent retching and inability to tolerate oral intake, and a recovery or convalescent phase. Between attacks individuals are usually well and asymptomatic. Common accompanying features include abdominal pain, lethargy, low-grade fever, and sensitivity to light or sound.

Causes, associations and triggers

The exact cause of CVS is not fully understood. It is considered part of a group of periodic syndromes that are associated with migraine in children; many people with CVS have personal or family histories of migraine. Episodes are often precipitated by identifiable triggers such as viral infections, emotional stress, sleep deprivation, fasting, certain foods, or motion sickness. Some medications and metabolic or hormonal changes may also precipitate attacks.

Evaluation and diagnosis

Diagnosis is clinical and relies on a characteristic pattern of recurring, stereotyped attacks with symptom‑free intervals and exclusion of other causes of vomiting. Physicians typically evaluate for gastrointestinal, metabolic, neurologic and endocrine disorders to rule out alternative explanations. Investigations may include blood tests, urine studies, and imaging when indicated; many tests are normal between episodes.

Management

Treatment aims at relieving acute attacks, preventing dehydration, and reducing attack frequency. During an episode, care focuses on rehydration, antiemetic and analgesic medications, and supportive measures such as rest and temperature control. Preventive strategies may include lifestyle changes (regular sleep and meals, trigger avoidance) and, for frequent or severe cases, prophylactic medications which are chosen based on age and coexisting conditions. Psychological support and education for patients and families are often helpful.

Prognosis and important distinctions

Many children with CVS improve with time and some later develop typical migraine headaches. For others, episodes can persist into adulthood. It is important to distinguish CVS from acute gastroenteritis, eating disorders, and other causes of recurrent vomiting; chronic cannabinoid use can produce a similar cyclic vomiting pattern (cannabinoid hyperemesis) and should be considered in the history. Timely recognition reduces unnecessary investigations and helps focus care on prevention and supportive treatment.

• Key signs: recurrent stereotyped vomiting episodes, symptom‑free intervals.
• Common triggers: infections, fasting, stress, certain foods.
• Associated with: family history of migraine, periodic syndromes of childhood.
• Related concept: severe vomiting itself—see vomiting.