Usually, bad breath, nausea and vomiting may be caused by stomach diseases, intestinal diseases, diabetes and other reasons. 1. Stomach disease: it may be related to Helicobacter pylori infection causing gastritis, gastric ulcer and other diseases, because Helicobacter pylori can secrete toxins, which can appear the phenomenon of bad breath, and when the toxins stimulate the gastric mucous membrane to produce inflammation, it may affect the nerves of the gastrointestinal tract. Therefore, under the action of many factors, the symptoms of bad breath, nausea and vomiting are produced. 2. Intestinal diseases: such as intestinal obstruction and other intestinal diseases, resulting in intestinal blockage, intestinal food can not be normal circulation, resulting in nausea, vomiting and other symptoms, food stays in the intestinal tract for a long time, the patient will show the symptoms of bad breath. 3. Diabetes: If diabetic patients combined with ketoacidosis, there will be a typical rotten apple flavor when exhaling, some patients will also be accompanied by nausea, vomiting and other symptoms. In addition, bad breath, nausea and vomiting can also be seen in other diseases, it is recommended that patients seek medical attention in a timely manner to avoid delay.