A child’s breath stinks, considering that it may be related to indigestion, oral diseases and other reasons. 1. Indigestion: when indigestion slows down the peristalsis of the gastrointestinal tract, a large amount of food is deposited in the gastrointestinal tract for a long time, which will produce a foul odor after fermentation. 2. Oral disease: gingivitis, periodontitis and other oral inflammatory diseases, a large number of bacterial growth and reproduction in the oral cavity, anaerobic bacteria will decompose food debris, resulting in foul-smelling gas, which can also lead to a small child’s breath stinks. Small children with smelly breath, there are other reasons, such as Helicobacter pylori infection, etc. Parents are advised to take their children to the hospital stomatology or gastroenterology as soon as possible, in order to clarify the cause of the disease.