Always having stomach acid may be caused by gastroesophageal diseases, mental stress, improper diet and so on. 1. Gastroesophageal diseases: Stomach acid is hydrochloric acid secreted in gastric juice. When there are gastritis, gastric ulcer, reflux esophagitis and other gastric diseases, it may lead to increased secretion of gastric acid and the symptoms of always having acid in the stomach, as well as nausea, vomiting and other symptoms. 2. Mental factors: When there are mental symptoms such as mental tension and stress, the cerebral cortex dysfunction may also stimulate the secretion of gastric acid to increase, and the symptoms of always having stomach acid. 3. Improper diet: When taking too much food such as chili, onion, sweets, etc., it may also stimulate the gastric mucosa and increase the secretion of gastric acid, which will cause the symptoms of acidity. Therefore, once the symptoms of acidity appear, you need to further check the gastroscopy and other programs to find the cause.