Inclusion Criteria:  Age 18 years or older at registration. Diagnosis of gastroparesis as documented by gastric emptying scintigraphy (4-hour emptying after a low-fat meal with any combination of 2- and 4-hour retention of >60% and 10%, respectively), or Chronic Unexplained Nausea and Vomiting (CUNV). Ongoing symptoms (i.e. Nausea and vomiting, bloating, and abdominal pain) with a nausea score of 3 or more on the patient assessment of upper gastrointestinal disorders-symptom severity index (PAGI-SYM) scale at baseline (moderate to severe nausea). Exclusion of other causes of symptoms such as mechanical gastrointestinal obstruction, uncontrolled esophagitis, peptic ulcer disease, etc. By standard radiographic or endoscopic tests. Use of the following medications on an as-needed basis: ondansetron, promethazine or prochlorperazine but no more than four times a day.  Exclusion Criteria:  Another active disorder, which could explain symptoms in the opinion of the investigator. Age < than 18 years. Pregnancy or nursing. A previous surgery of the upper gastrointestinal tract, including vagotomy. Use of narcotics more than 3 days per week. History of prolonged QT interval or a history of clinically significant arrhythmia. Abnormal baseline ECG (e.g. Second- and third-degree heart block, atrial fibrillation, atrial flutter, recent history of ventricular tachycardia or ventricular fibrillation, or clinically significant premature ventricular contraction). Previous bilateral or right cervical vagotomy. Uncontrolled high blood pressure. Currently implanted with an electrical and/or neurostimulator device, including but not limited to cardiac pacemaker or defibrillator, vagal neurostimulator, deep brain stimulator, spinal stimulator, bone growth stimulator, or cochlear implant. History of carotid endarterectomy or vascular neck surgery on the right side. Implanted with metal cervical spine hardware or has a metallic implant near the gammaCore stimulation site. Any other condition, which in the opinion of the investigator would impede compliance or hinder the completion of the study. Failure to give informed consent.