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. 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.

Between episodes of vomiting, many patients experience symptoms that can include gastroesophageal reflux disease (GERD) symptoms, mild nausea, fatigue, abdominal pain, and syncope.

Studies show a link between cyclic vomiting syndrome and migraine headaches. Other associations include metabolic (food allergy), mitochondrial, catamenial, and endocrine disorders.