1, oral disease gingivitis, periodontitis patients with bleeding gums, sulcus overflowing pus, a large amount of calculus or soft scale dirt attached, or food embedded, by bacterial fermentation, the production of hydrogen sulfide, indole and ammonia, thus producing odor. Periodontal abscesses due to acute attacks of periodontitis are mixed infections of aerobic and anaerobic bacteria. Necrotizing gingivitis has a specific odor from necrotic tissue in the mouth together with clostridia and spirochetes. Deep cavities often contain food, which can give off foul odor when fermented by bacteria or untreated pulp gangrene. Dentures that are not frequently brushed or cannot be removed, infected wounds after tooth extraction or wounds that are not healed by chronic osteomyelitis are also causes of bad breath. Malignant tumors in the oral cavity can emit a strange bad odor. Eating onions, garlic, garlic, leeks, smoking, drinking and other food with fishy odor, can send out the unique odor of food. Due to indigestion to thick and greasy tongue or febrile disease, serious illness so that the normal self-cleaning and thick and greasy tongue, can be issued because of the tongue fermentation and odor. In addition, black hair tongue, cracked tongue, etc. by bacterial fermentation also emits odor. 2, near the oral cavity tissue lesions purulent tonsillitis, purulent maxillary sinusitis, atrophic rhinitis, atrophic pharyngitis due to purulent secretions or in the issuance of odor. In addition, syphilitic ulcers, pharyngitis, nasal tumors, etc., can give off foul odor. 3, systemic diseases such as lung abscess, bronchiectasis, tuberculosis, etc. can exhale foul odor; gastrointestinal tract dysfunction, gastrointestinal bleeding, long-term constipation can cause bad breath; diabetic ketosis patients exhale acetone gas; uremic patients exhale rotten fruit odor; metal aluminum, mercury and organic poisoning, there is also an abnormal smell occurs. The main treatment is to remove the various causes of halitosis, regular dental cleaning, remove tartar, soft tartar, eliminate gum inflammation. Keep your breath fresh in addition to pay attention to brushing and rinsing, chewing gum often to increase the self-cleaning effect of the mouth. You can also use a spray containing drugs and fragrances to spray the mouth and throat.