Sourness in the mouth is usually due to heat in the liver and stomach or dietary stagnation in the stomach and intestines. Among the five organs corresponding to the five tastes, sourness corresponds to the liver. When there is heat in the liver and stomach, there will be acidity in the mouth, accompanied by headache, redness and swelling of the eyes, dizziness, burning sensation in the stomach, hyperphagia, increased food intake, frequent hunger, hyperactive intestinal sounds, pain in the small of the abdomen on both sides, etc. It is recommended to give treatment to clear the liver and stomach, and can be taken orally with Shu Liver Fast Stomach Pill. When the diet is difficult to digest and stagnant in the gastrointestinal tract, the mouth will also become acidic and sour, accompanied by a lack of desire to eat and drink, foul stools and other symptoms, it is recommended to give treatment to eliminate food and guide stagnation.