Sudden diarrhea may be caused by acute gastroenteritis, functional dyspepsia, cholera and other causes. 1. Acute gastroenteritis: patients show a rapid onset, symptoms are more obvious, patients show vomiting and diarrhea, stomach pain, dehydration and other symptoms. 2. Functional dyspepsia: the etiology is more complex, may be caused by gastric power defects, stomach acid, patients manifested as stomach pain, stomach distension, diarrhea, vomiting and other symptoms. Patients should do abdominal examination and gastroscopy if necessary. 3. Cholera: it is an infectious disease, an acute gastrointestinal infectious disease caused by Vibrio cholerae, which is characterized by rapid onset, rapid spread, wide spread, and can cause pandemics, patients show sudden diarrhea, vomiting and dehydration, muscle spasms, which will soon cause circulatory failure, and even life-threatening. Patients should promptly do stool examination, blood routine, urine routine examination. Sudden diarrhea diarrhea more than may have many other reasons, the patient needs to consult the doctor in a timely manner to clarify the cause of standardized treatment, to avoid delays in the condition.