Exhaling a rotten egg odor from the mouth is not necessarily a stomach problem, but may also be an oral problem, tonsil problem, etc., which requires differential diagnosis. 1. Stomach problems: If you suffer from gastritis, gastric ulcers and other stomach diseases, there can be food digestion and absorption disorders, so that the food stays in the stomach for too long, resulting in a rotten egg taste in the mouth. 2. Oral problems: If you suffer from dental caries and other oral diseases, when food residues remain in the cavity, after the fermentation of oral bacteria, there may be a phenomenon of rotten egg flavor exhaled from the mouth. 3. Tonsil problems: If the tonsils are pus-filled and inflamed, purulent secretions in the role of bacteria can cause a rotten egg odor in the mouth. There are many other reasons for the rotten egg odor, it is recommended that the person who has a rotten egg odor go to a regular hospital in time to clarify the cause of the disease, and standardized treatment under the guidance of the doctor.