There is very little controlled data on the preventative treatment for Cyclic Vomiting Syndrome. The existing evidence consists of small, retrospective clinical series that evaluate symptomatic responses to five medications including cyproheptadine, propranolol, amitriptyline, phenobarbital and pizotifen (n >10). These published data consist of uncontrolled or retrospective reports. In addition, varying inclusion criteria and outcomes (i.e. obtained by family recall) were used in these studies limiting the basis upon which to compare relative effectiveness.