The common clinical causes of yellow tongue and bad breath are poor oral hygiene and Helicobacter pylori infection. 1. Poor oral hygiene: some people do not do a good job of oral hygiene cleaning work, teeth crevices remain in the food debris, bacteria will grow in the oral cavity, resulting in yellow teeth, tooth decay, bad breath, yellow tongue and other symptoms. It is recommended that this group of people should do a good job of daily oral cleaning, early in the morning as well as before going to bed should be carefully brushed, gargling, etc., and at the same time to the hospital on a regular basis in order to ensure that the oral health of dental scaling. 2. Helicobacter pylori infection: Helicobacter pylori is an anaerobic bacterium that usually resides in the stomach and may also survive in dental plaque. When the mouth is infected with Helicobacter pylori, it will cause serious breath, and in severe cases, there will be a special oral odor, while the appearance of the tongue will also be affected, the keratinized epithelium on the tongue thickening as well as the related bacterial growth, reproduction state changes, etc., the bacteria will make the color of the tongue change and appear as yellow. Simple cleaning is not able to remove this flavor, you need to carry out anti-Helicobacter pylori treatment under the guidance of a doctor, taking omeprazole, bismuth pectin, amoxicillin, clarithromycin and other quadruple therapy drugs. If the symptoms of yellow tongue and bad breath persist, it is recommended to go to the hospital as soon as possible for examination to clarify the specific cause of the disease for further targeted treatment. The medication should be prescribed by the doctor.