Long-term bad breath is usually caused by poor oral hygiene, gastrointestinal dysfunction, Helicobacter pylori infection, oral diseases, etc., can be prescribed by scaling, oral domperidone and other drugs, the use of quadruple therapy and other treatments, if necessary, can be extracted to eliminate bad breath. 1. Poor oral hygiene: poor oral hygiene can directly lead to bad breath. Especially for patients suffering from dental calculus, first of all, we should brush our teeth carefully, perform ultrasonic scaling and deep scraping to remove dental calculus and soft tartar. 2. Gastrointestinal dysfunction: gastrointestinal function decline, food is not easy to be digested and absorbed in the intestinal tract leading to bad breath, the patient can use famotidine, omeprazole and domperidone, itopride and other inhibitors of gastric acid and gastrointestinal dynamics. Drugs should be taken under the guidance of a physician. 3. Helicobacter pylori infection: a condition that can lead to bad breath and requires treatment with quadruple therapy, including proton pump inhibitors (e.g., omeprazole), bismuth (e.g., fructose bismuth), and two antibiotics (e.g., amoxicillin, clarithromycin, etc.) for treatment. 4. Oral disease: Severe caries may lead to food congestion and cause bacterial growth. Patients can visit the dentist to remove the decayed and diseased tissue or have the decayed teeth extracted. There are many causes of long-term bad breath, you should go to the hospital in time for relevant examinations, the doctor to clarify the cause of the disease, and guide the treatment, to avoid delaying the condition, resulting in adverse consequences.