Clinically there is no long-term bad breath to be wary of which four diseases, long-term bad breath may be nasal diseases, digestive diseases, oral diseases and other causes. 1. Nasal diseases: if the patient suffers from chronic sinusitis and other diseases, due to long-term chronic inflammation stimulation, can produce a large amount of purulent secretions, appearing long-term bad breath. 2. Digestive system diseases: when the patient suffers from gastric ulcer, gastritis and other diseases, can lead to abdominal distension, abdominal pain and other symptoms, affecting the secretion of digestive juices, the phenomenon of long-term halitosis. 3. Oral disease: if there is periodontitis, gingivitis and other diseases, it will be easy to appear in the neck of the teeth attached bacteria, resulting in bacteria will decompose food residues, may appear long-term bad breath. Long-term bad breath patients should go to the hospital in a timely manner, clear causes under the guidance of the doctor standardized treatment, so as not to delay the condition.