Oral acidity is related to dietary or mental factors, and may also be an abnormality in the function of the oral salivary glands. 1. Often eat sweet or acidic food, or spicy and stimulating food, causing an increase in gastric acid in the stomach, or mental tension or stress, long-term fatigue triggered by nervous disorders, can also cause an increase in gastric acid. 2. Stomach acid reflux into the mouth will appear in the mouth acidic feeling. Oral salivary gland secretion abnormality, saliva reduction triggered by oral dryness, oral bacterial fermentation of acidic substances is difficult to be rinsed off, will also appear oral acidity. Therefore, acidity in the mouth is commonly caused by the above reasons, you can go to the stomatology department or the neurology department, and follow the doctor’s advice to deal with.