Exhalation after eating certain foods or drugs (such as garlic, wine, etc.) contains its odor, and the mouth can directly emit its special breath. Foreign body corruption, such as food scraps in the teeth, corruption, odor, larynx, nose, pharynx, foreign bodies for too long or cause local inflammation, so that the secretions (snot, sputum, saliva, etc.) decomposition decay produces odor. Some bacteria in the respiratory tract (various anaerobic bacteria) decompose proteins and starch, producing odorous gas. Tissue destruction or necrosis can produce rotten egg odor stench. When there is an increase in ketones and urea in the blood (such as diabetic ketosis, uremic acidosis), there can be ketones when exhaling, and the breath of urine. So, what are the causes of abnormal breath symptoms? The following are the causes of abnormal breath symptoms. 1, nasopharyngeal diseases: odorous rhinitis (chronic rhinitis), nasopharyngeal cancer, maxillary sinus cancer, acute tonsillitis, pharyngitis, etc. 2, oral diseases: periodontal disease, gum infection and poor oral hygiene, tongue inflammation, oral inflammation (post-extraction infection, Enderson’s stomatitis, walking horse chancre), oral cancer, laryngeal cancer, etc. 3.Digestive tract diseases: esophageal diverticulum, esophageal tumor, esophageal stricture, cardia cancer with ulcer, gastritis, dyspepsia, constipation, esophageal hiatal hernia, gastric cancer, gastrointestinal infection, pyloric obstruction, intestinal obstruction, gastrocolic fistula, peritonitis, appendicitis, advanced chronic liver disease, etc. 4.Bronchial diseases: purulent bronchitis, bronchiectasis combined with anaerobic bacterial infection, bronchopleural fistula due to various causes (hepatoma, abscess chest, etc.). 5, pleural lesions: purulent pleurisy with bronchopleural fistula, bronchopleural fistula formed by liver abscess breaking down into the pleura, etc. 6, lung diseases: lung abscess and lung infection combined with anaerobic bacteria, pulmonary ring gangrene, tuberculosis cavity, pulmonary cyst with infection, lung cancer, etc. 7, other: diabetic ketoacidosis, starvation, dyspepsia and malabsorption, salicylic acid poisoning, uremia, taking poison, alcohol poisoning, oral drugs, hyperthermia, respiratory or upper gastrointestinal bleeding, occupational chemical poisoning, etc.