Sudden onset of nausea with no obvious cause or medical history should be noted if it is related to hepatitis, nephritis, pregnancy, etc. Nausea due to gastritis or dyspepsia may be accompanied by a history of ingestion of unclean food and symptoms such as bloating and diarrhea. Nausea due to cardiac insufficiency may be accompanied by swelling of the lower extremities and weakness, while hepatitis and nephritis may have no other symptoms in the early stage of development, with nausea as the first manifestation. Nausea due to hepatitis will have elevated glutathione and glutamic oxalacetic transaminase, while nephritis will have elevated creatinine and urea nitrogen, and early pregnancy will have a significant increase in HCG.