Bad breath after eating sweets is due to the fact that the sugar in sweets can be broken down into lactic acid-like substances, which help bacteria to multiply and lead to bad breath. Sweets generally contain sugar, which can be broken down into lactic acid-like substances, which become the culture medium for bacteria and can easily lead to bad breath. At the same time, sugar itself is a nutrient for bacterial reproduction, which also promotes bad breath. Bad breath can also be caused by gastrointestinal disorders. Gastric ulcers often cause bad breath, mainly due to the fermentation of food by Helicobacter pylori bacteria in the stomach. In addition, dental calculus can also cause bad breath because of the bacteria and food debris attached to the calculus, resulting in bacterial fermentation and the need for dental cleaning treatment. It is recommended to consult a hospital to identify the cause of bad breath and treat the symptoms.