Sudden hiccups may be caused by improper diet, indigestion, mental factors, neurological tumors, central nervous system diseases and so on. 1. Improper diet: Eating faster, inhaling too much air while eating, resulting in diaphragmatic contraction and hiccups. 2. Indigestion: the food accumulated in the stomach will be fermented and produce more gas, which will stimulate the diaphragm and cause hiccups, bloating and nausea. 3. Mental factors: excessive mental tension, anxiety and stress cause the diaphragm to spasm and hiccups. 4. Tumor disease outside the nervous system: such as mediastinal tumor, esophageal cancer, thoracic aortic aneurysm and so on, which can cause hiccups. 5. Diseases of central nervous system, such as meningitis, cerebral hemorrhage, brain tumor, cerebral infarction and so on. It is recommended to consult a doctor in time to find out the cause of the disease and give treatment under the doctor’s instruction.