Baby bad breath may be caused by poor oral hygiene, food residue storage and other bad habits, can be improved by regular brushing, pay attention to oral cleaning, etc., may also be due to some oral medicine stimulation. In addition, if the baby has a long-term bad breath performance, may also be due to oral, throat or stomach diseases, which need to actively find the cause, and then corresponding treatment: a. Common causes: 1, taking drugs: some oral drugs, can produce a certain stimulation of the oral cavity, resulting in oral environment changes, thus causing bad breath baby; 2, oral diseases: if the baby has dental caries, oral ulcers, or gums, periodontal inflammation and other oral diseases. Periodontal inflammation and other oral diseases, coupled with bad oral habits, may cause the reproduction of bacteria inside the mouth, resulting in inflammatory infiltration, which in turn causes bad breath in babies; 3, pharyngeal disease: pharyngitis, tonsillitis, sinusitis or upper respiratory tract infections and other lesions can involve the throat, resulting in local inflammatory exudation from the affected area of the throat, and the baby may smell bad when exhaling gas from the mouth; 4, stomach diseases. Gastroesophageal reflux disease, Helicobacter pylori infection, dyspepsia or gastroduodenal ulcer and other gastroesophageal diseases may lead to acid reflux in the stomach, which leads to bad breath in the baby, and the odor is aggravated when exhaling. Second, the solution: 1, maintain oral environmental hygiene: generally brush twice a day, parents should apply the correct way to brush the baby’s teeth, try to avoid oral foreign body residue; 2, regulate the baby’s diet: should pay attention to the appropriate amount of fresh vegetables and fruits, as well as fresh meat, eggs and milk. Reduce or avoid drinking fruit juice, drinks with high sugar content, and try to eat less or no snacks with high sugar content as well as dairy products to avoid tooth decay or periodontal disease; 3. Stop using oral medication: If the baby needs to take oral medication that may cause bad breath due to other diseases in the body, it should be reduced or stopped under the guidance of the doctor after taking enough courses to reduce the impact on oral odor; 4. Find and treat the primary disease. If bad breath is still present after maintaining oral hygiene or stopping the use of oral medication, it may be caused by a disease. At this time, you need to take your baby to the hospital to identify the cause of bad breath and treat the cause.