Halitosis caused by stomach and intestines may be caused by physiological reasons or pathological reasons such as long-term constipation and Helicobacter pylori infection. It is necessary to pay attention to oral hygiene, treatment through drugs and other ways. 1. Physiological reasons: consumption of stimulating foods such as onions and garlic, reduced salivary secretion during sleep, transient halitosis caused by massive bacterial decomposition of food residues, or caused by poor oral habits. You can brush your teeth in time after consuming stimulating foods and clean your oral hygiene. 2. Pathologic causes: (1) Long-term constipation: patients with long-term constipation may suffer from halitosis due to fecal odorant and ammonia in feces, which may result in bad breath due to the reflux of odor into the oral cavity. Lubricating laxatives such as Keserol can be used to lubricate the intestinal wall and soften the stool so that the stool can be easily discharged; prokinetic agents such as mosapride can also be used to promote gastrointestinal peristalsis. (2) Helicobacter pylori infection: Helicobacter pylori can not only reside in the stomach, but also in the oral parasitism, the most content in dental plaque. It breaks down urea and other substances in the mouth to produce an unpleasant ammonia odor, leading to bad breath. A quadruple regimen containing bismuth, such as omeprazole + clarithromycin + amoxicillin + bismuth potassium citrate, can be prescribed for H. pylori eradication. Halitosis caused by stomach and intestines can also be seen in other diseases, it is recommended to go to the hospital to clarify the cause of the disease, under the guidance of the doctor for treatment.