Differential diagnosis: Nausea is a nonspecific symptom that can be caused by a variety of reasons. Acute episodes of nausea and vomiting without abdominal pain can be seen in infectious gastroenteritis, food poisoning, drug factors, systemic infections, metabolic disorders, migraine, increased intracranial pressure, or vaginitis. Acute vomiting with abdominal pain can also be caused by a variety of diseases, such as intestinal obstruction, but there are often clear clues. Therefore, the differential diagnosis of acute nausea and vomiting is not too difficult in most cases. The differential diagnosis of chronic nausea is a little more difficult, listing some of the etiologies of nausea and vomiting. Early pregnancy reactions, drug factors (cancer chemotherapy drugs, anesthetics, hormonal agents, antibiotics, antivirals and cardiovascular medications) can lead to nausea and vomiting. Organic gastric diseases, such as pyloric obstruction due to tumors or ulcers, can present with nausea and vomiting, accompanied by abdominal pain and weight loss. Gastroparesis is also a cause of chronic nausea, but its pathogenesis is unknown and the diagnosis depends on the exclusion of other organic diseases. patients with GERD may present with nausea, but often mistake reflux for vomiting. Patients with labyrinthine abnormalities are indicated by history and physical examination, such as vertigo or nystagmus. Cyclic vomiting syndrome is seen in pediatric patients with migraine. Some other diseases that cause nausea and vomiting, such as intestinal obstruction, pancreatitis, cholecystitis, hepatitis, adrenal insufficiency, renal failure, electrolyte disorders and narcotic withdrawal symptoms, are easier to diagnose because they mostly have sufficient clinical and ancillary examination evidence. Methods of diagnosis and treatment: In most cases, a clear diagnosis and treatment plan will be obtained after careful history taking, physical examination and necessary laboratory tests (routine blood, complete biochemical set, pregnancy test, amylase, lipase). If the diagnosis is still unclear after the initial evaluation, antiemetic or prokinetic drugs, such as gastroflucan, may be given empirically first. Clinical effectiveness studies for various antiemetics have shown that anticholinergic drugs (scopolamine) and antihistamines (meclizine, diphenhydramine, hydroxyzine) are more effective for motility disorders and abnormalities of vagal function. Phenothiazines (e.g., chlorpyrazine 5-10mg orally tid or qid, or 25mg suppositories in anal bid, or 2.5mg-10.0mg intravenously q3-4h to a maximum dose of 40mg/d) are effective for a variety of causes of nausea and vomiting. Other phenothiazines include promethazine, thiopiperazine, chlorpromazine, and endorphin. Pentoxifylline receptor antagonists, such as entaindenone, are effective but expensive and widely used in chemotherapy patients. There are fewer types of prokinetic drugs, and gastroflucan 5mg-10mg orally qid is commonly used. For many patients, empirical treatment alone is not sufficient, and further investigations are needed to clarify the etiology, including EGD, gastric emptying test, abdominal plain film and CT, cranial MRI and psychiatric evaluation, which should be selected according to the nature, duration and severity of the patient’s symptoms.