Old hiccups may be related to gastroesophageal reflux, indigestion, dietary factors and so on. 1. Gastroesophageal reflux: the gas and food remaining in the stomach refluxes to the esophagus with stomach acid, causing irritation to the esophagus, leading to spasm of the diaphragm and the symptom of frequent hiccups. 2. Indigestion: the slowing down of gastrointestinal peristalsis leads to the accumulation of food in the body, which produces a large amount of gas after fermentation, causing hiccups and accompanied by bad smell. 3. Dietary factors: If you eat too much gas-producing foods, such as sweet potatoes, onions, garlic, and carbonated beverages, frequent hiccups can also occur. Old hiccups can also be caused by gastritis, gastric ulcer, intestinal obstruction, craniocerebral diseases and so on. If frequent hiccups occur, it is recommended to go to the hospital for a systematic examination to clarify the cause of the disease and then early treatment to avoid delays.