Common causes of sudden nausea and regurgitation include: pregnancy reaction, acute gastroenteritis, acute pancreatitis, food poisoning, intracranial lesions and so on. 1. Pregnancy reaction: Women of childbearing age who experience symptoms such as menopause, sudden nausea and regurgitation are usually suffering from early pregnancy reaction. It is caused by the increase in hormone levels during pregnancy, which is a normal physiological phenomenon. 2. Acute gastroenteritis: usually due to low immunity, overeating, improper diet, etc., induced by acute inflammation of the gastrointestinal mucosa, manifested in sudden nausea, regurgitation, abdominal pain and other symptoms. Loperamide and other drugs can be used as prescribed by the doctor. 3. Acute pancreatitis: acute inflammation of the pancreas can cause congestion and edema of the surrounding intestinal wall and mesentery, and autonomic nerve inhibition, leading to gastrointestinal dysfunction, and then sudden nausea, vomiting and regurgitation. 4. Food poisoning: If you accidentally ingest food containing toxins or food contaminated with toxins and suffer from food poisoning, which can be manifested as sudden nausea, regurgitation, diarrhea and other symptoms, it is recommended to go to the hospital in time for gastric lavage. 5. Intracranial lesions: For example, cerebral edema, cerebral hemorrhage, cerebral infarction and other diseases can lead to a significant increase in intracranial pressure, which in turn causes sudden nausea, regurgitation, vomiting and other symptoms. As you can see, sudden nausea and regurgitation can be caused by many reasons, it is recommended to go to a regular hospital in time to get a clear diagnosis and targeted treatment.