Cyclic vomiting syndrome (CVS) may be the most severe recurrent vomiting disorder in humans. CVS is characterized by a sudden onset of rapid-fire vomiting, usually beginning in the early morning hours or upon wakening. It has a peak vomiting intensity of every 5-10 minutes (6-12 emeses) and episodes last between 2 hours and 10 days. These episodes of acute vomiting occur on average once every 2 to 4 weeks. The child returns to completely normal health between vomiting episodes. Children are diagnosed based on their specific vomiting pattern and a lack of positive findings on laboratory testing.