Dry mouth, dry throat and bitter mouth may be related to oral food residue, indigestion, periodontitis, sinusitis and other factors, according to the specific circumstances of reasonable judgment. 1. Oral food residue: If oral hygiene is not clean, there is often food residue, coupled with the daily drinking water is too little, after a long time the residual food will be oxidized, which will lead to dry mouth, dry throat, bad breath and so on, daily attention to maintain oral hygiene. 2. indigestion: if the daily eating habits are not proper, often overeating, will cause chronic damage to the stomach, resulting in indigestion, which will lead to bad breath, dry mouth phenomenon, daily to develop good eating habits. 3. periodontitis: if the periodontium is infected by bacteria and other pathogenic microorganisms, it will cause damage to the local periodontal tissues, red and swollen gums, loose teeth and other symptoms, usually accompanied by bad breath, dry mouth, dry throat, etc., it is necessary to keep teeth clean. 4. Sinusitis: If the sinuses are infected by pathogenic microorganisms such as bacteria and viruses, a large amount of fluid secreted by the sinus mucosa is damaged, due to the nasal cavity is connected to the oral cavity, which in turn appears as dry mouth, halitosis, dry pharynx and so on. If the problem of dry mouth, dry throat and bad breath can not be effectively resolved, it is necessary to go to the hospital in time to avoid other serious effects on the body.