Fecal odor in the mouth is mainly due to gingivitis and chronic gastritis, may also be related to liver disease, it is recommended that further examination to clarify the causes of fecal odor. 1. Gingivitis: Inflammation of the gum tissue caused by plaque, which breeds a large amount of plaque, decomposes the ingredients in food debris, and produces odorous gas, thus causing fecal odor in the mouth. 2. Chronic gastritis: the stomach, stimulated by inflammation, secretes excessive gastric acid, which ferments in the body and produces a large amount of gas, which rises to the mouth through the digestive system, resulting in the symptom of fecal odor in the mouth. 3. Liver disease: when the liver is abnormal or damaged, it affects the normal metabolism and makes the bile flow back into the esophagus, and then it reaches the mouth through respiration, and then the phenomenon of fecal odor in the mouth will appear. After the appearance of fecal odor in the mouth, it is recommended to go to the hospital in time to clarify the causes of fecal odor, pay attention to a light diet in daily life, avoid spicy stimulating food, can reduce the symptoms of fecal odor in the mouth.