Cyclic vomiting syndrome is an idiopathic disorder characterized by recurring episodes of forceful vomiting followed by an absence of vomiting between cycles. Onset is acute. Episodes may last 24-48 hours in children or 3-6 days in adults; they follow a pattern unique to the patient. The average age of diagnosis is 9.6 years of age. Symptom-free intervals vary by individual but average 3 months.

Prodromal or concurrent signs and symptoms of cyclic vomiting syndrome include nausea, pallor, abdominal or epigastric pain, lethargy, headache, anorexia, diarrhea, photophobia, and fever. Studies show a link between cyclic vomiting syndrome and migraine headaches. Other associations include metabolic (food allergy), mitochondrial, catamenial, and endocrine disorders.