Indigestion can lead to bad breath for the following reasons: 1, in indigestion, a large amount of food eaten in the stomach as well as the intestinal tract to stay, food fermentation in the gastrointestinal tract will appear putrid smell, so there will be bad breath. 2, part of the cause of indigestion is the presence of Helicobacter pylori infection, when the Helicobacter pylori in the stomach to reproduce, grow, can produce a certain amount of gas, which leads to the appearance of bad breath. 3, there are A part of the patients with indigestion is caused by the intestinal flora imbalance. Because the intestinal flora is normally in a state of balance, probiotic bacteria are the dominant flora, when the intestinal flora is dysbiosis, pathogenic bacteria become the dominant flora. The pathogenic bacteria produce tasty gas during the digestion of food and are expelled from the mouth, and then bad breath occurs.