Heartburn is mostly caused by increased stomach acid. The main causes of excessive stomach acid are as follows: 1. Eating too much food with stimulating properties, such as spicy and aggressive food, too cold and too hot food, coffee, strong tea, etc., will stimulate the gastric mucosa to secrete large amounts of stomach acid. 2. Bad emotions, excessive tension or excessive fatigue can lead to dysfunctional gastric acid secretion and promote the secretion of stomach acid. 3. Pathological factors, acute and chronic gastritis, gastric ulcer, duodenal ulcer, reflux esophagitis, often have heartburn and acid reflux, should be treated symptomatically. 4, long-term smoking and alcohol abuse, smoking and alcohol can stimulate the stomach and intestines, accelerate the blood circulation of the mucosa, leading to excessive secretion of stomach acid. 5, taking drugs, long-term use of drugs such as aspirin, pau d’arco, etc., can also damage the function of the stomach.