The main causes and treatments of bad breath are: 1. Bad oral hygiene, bad breath caused by too much food residue and bacteria on the teeth and tongue. The main methods are scaling, tooth surface polishing, subgingival scraping, root surface straightening and other periodontal treatment means. People with bad breath should brush their teeth carefully, and gently brush the surface of the tongue while brushing teeth, which will help to reduce the phenomenon of bad breath. 2, Stomach fire will lead to bad breath, treatment can be taken to strengthen the stomach and eliminate food tablets, Niuhuang Shangqing Pills, large hawthorn pill, while the diet should be light and easy to digest. 3, patients suffering from reflux esophagitis, gastric ulcer, gastric power deficiency, due to food stagnation in the stomach stay for too long, will also lead to bad breath. In this case, you need to go to the gastroenterology department to treat the corresponding disease, such as taking omeprazole for gastric ulcer.