Bitter mouth is an abnormality of oral taste function, bad breath is a bad odor from poor oral hygiene, often affecting normal social interaction, and requires symptomatic treatment according to the cause. There are various taste papillae on the tongue, and the tongue papillae that feel bitter taste are at the root of the tongue. Bitter mouth is a taste abnormality, which may be caused by poor digestion in the gastrointestinal tract, and can be treated with oral probiotic drugs or purgative drugs, or it may be an inflammatory reaction. The cause of bad breath is complex, with the type of food eaten, oral diseases, digestive tract diseases and some causes are not clear. First of all, take care not to eat odorous foods such as: onions, raw onions, raw garlic, etc. Go to stomatology and gastroenterology department to check whether related diseases. It is caused by poor oral hygiene, not properly brushing teeth after eating, food residue or soft scale accumulation to form gingivitis or periodontitis, periodontitis will show loose teeth and periodontal abscess, there will be oral odor, need to go to periodontology or dentistry for treatment. It may also be caused by tooth decay, pulp tissue septic necrosis and bad breath, which requires dental treatment. Bad breath may also be caused by digestive system diseases, which requires a visit to the gastroenterology department. Therefore, it is necessary to further examine the cause of bad breath and find out the cause for treatment, pay attention to a light diet and maintain oral hygiene.